Repair and Maintenance of Window and Split AC

Repair & Maintenanceof Window & Split AC Student Workbook Written and Published by: Shri Technologies #401, Bashyam Kamineni Residency, Yousufguda, Hyderabad -500 045. Phone :040-66 33 77 88,66 366 789, [email protected] Web: www.shritechnologies.com



Contents 1 4Session 1: Introduction to Refrigeration & Air-conditioning 11Session 2: History of Refrigeration & Air-conditioning 13 15Session 3: Industry Prospects for Refrigeration and Air Conditioning 18Session 4: Career Prospects for Refrigeration and Air Conditioning 24Session 5: Skills required for Split or Window AC Mechanic 26Session 6: Common, Measuring and special Tools in Air Conditioning works 28Session 7: Common Terminology 32Session 8: Equipment’s and Meters in R&AC trade 34Session 9: Heat and related terms 38Session 10: Temperature and related terms. 39Session 11: Refrigeration related Pressure 41Session 12: Force, Work, Energy, Power 44Session 13: Tube & Pipe and their fittings (Capillary Tube) 50Session 14: Soldering, Brazing & gas weldingSession 15: Air Conditioning (cooling) System and its unitSession 16: Vapor Compression Refrigeration system

Contents 54 59Session 17: Simple Absorption Refrigeration System 62 64Session 18: Compressors 65 67Session 19: Sealed (Hermetic) and semi sealed compressorSession 20: Performance of the compressor 68Session 21: Oil & Lubricating system of compressorSession 22: Condensers 77Session 23: Refrigerant flow controllers, Hand expansion valve and capillary tube; Thermal 79Expansion valve. Automatic and Thermal Expansion Valve. High & Low side float and Sole- 81noid valve. 83Session 24: Evaporator in both Window & Split AC 85Session 25: Receiver 87Session 26: Accessories of refrigeration system 90Session 27: Refrigerants (CFC & Non CFC refrigerants) and Refrigerants Cylinder. 92Session 28: Greenhouse effect 102Session 29: Basic Electricity; Current, Voltage, Resistance measuring 106Session 30: Safety Precaution in electricity 107Session 31: Electrical; wiring diagram and Earthlings. (Open circuit, Short Circuit, Earth test- 109ing) 122Session 32: Over current (load) protector, Thermal fuse, Cooling fanSession 33: Pshychometer & Psychometric ChartSession 34: Air FiltrationSession 35: Window Air Conditioner, Installation, Servicing, Leaks,MaintenanceSession 36: Split Type AC Installation, Servicing

CCoonntteennttss 128Session 37: Charging, Evacuation & Purging 135Session 38: Trouble Shooting (Causes and Remedying) 1Session 39: Problems of AC MechanicSession 40: Customer 138Session 41: Safety Precaution & First Aids. 3 139 1641

1 Introduction to Refrigeration & Air-conditioningShri Technologies Literal meaning of refrigeration is the production of cold confinement relative to its surroundings. In this, Repair & Maintenance of Window & Split AC temperature of the space under consideration is maintained at a temperature lower than the surrounding atmosphere. To achieve this, the mechanical device extracts heat from the space that has to be maintained at a lower temperature and rejects it to the surrounding atmosphere that is at a relatively higher tempera- ture. Since the volume of the space which has to be maintained at a lower temperature is always much lower than the environment, the space under consideration experiences relatively higher change in temperature than the environment where it is rejected. The job of a refrigeration plant is to cool articles or substances down to, and maintain them at a temperature lower than the am- bient temperature. Refrigeration can be defined as a process that removes heat. The oldest and most well-known among refrigerants are ice, wa- ter, and air. In the beginning, the sole purpose was to conserve food. The Chinese were the first to find out that ice increased the life and improved the taste of drinks and for centuries Eskimos have conserved food by freezing it. At the beginning of the last century, terms like bacteria, yeast, mould, enzymes etc. were known. It had been discovered that the growth of microorganisms is temperature-dependent, that growth declines as temperature falls, and that growth becomes very slow at temperatures below +10 °C. As a consequence of this knowledge, it was now possible to use refrigeration to conserve food stuffs and natural ice came into use for this purpose.

2 Shri Technologies Refrigeration and Air-Conditioning Refrigeration and air conditioning is used to cool products or a building environment. The refrigeration or air conditioning sys- tem (R) transfers heat from a cooler low-energy reservoir to a warmer high-energy reservoir. There are several heat transfer loops in a refrigeration system as shown in Figure Thermal energy moves from left to right as it is extracted from the space and expelled into the outdoors through five loops of heat transfer:  Indoor air loop. In the left loop, indoor air is driven by the supply air fan through a cooling coil, where it transfers its heat to chilled water. The cool air then cools the building space.  Chilled water loop. Driven by the chilled water pump, water returns from the cooling coil to the chiller’s evaporator to be re-cooled.  Refrigerant loop. Using a phase-change refrigerant, the chiller’s compressor pumps heat from the chilled water to the condenser water.  Condenser water loop. Water absorbs heat from the chiller’s condenser, and the condenser water pump sends it to the cooling tower.  Cooling tower loop. The cooling tower’s fan drives air across an open flow of the hot condenser water, transferring the heat to the outdoors.Shri Technologies

3 Air-Conditioning Systems Depending on applications, there are several options / combinations of air conditioning, which are availa- ble for use: Air conditioning (for space or machines)  Split air conditioners  Fan coil units in a larger system  Air handling units in a larger system Questions What is refrigeration What are the different Explain the different air conditioning systemsShri Technologies Repair & Maintenance of Window & Split AC

4 Shri TechnologiesShri Technologies History of Refrigeration & Air-conditioning Refrigeration is a process in which work is done to move heat from one location to another. The work of heat transport is traditionally driven by mechanical work, but can also be driven by heat, magnetism, elec- tricity, laser, or other means. Refrigeration has many applications, including, but not limited to: household refrigerators, industrial freezers, cryogenics, and air conditioning. Heat pumps may use the heat output of the refrigeration process, and also may be designed to be reversible, but are otherwise similar to refrigera- tion units. Refrigeration has had a large impact on industry, lifestyle, agriculture and settlement patterns. The idea of preserving food dates back to the ancient Roman and Chinese empires. However, refrigeration technology has rapidly evolved in the last century, from ice harvesting to temperature-controlled rail cars. The intro- duction of refrigerated rail cars contributed to the westward expansion of the United States, allowing settle- ment in areas that were not on main transport channels such as rivers, harbors, or valley trails. Settlements were also popping up in infertile parts of the country, filled with new natural resources. These new settle- ment patterns sparked the building of large cities which are able to thrive in areas that were otherwise thought to be unsustainable, such as Houston, Texas and Las Vegas, Nevada. In most developed countries, cities are heavily dependent upon refrigeration in supermarkets, in order to obtain their food for daily con- sumption. The increase in food sources has led to a larger concentration of agricultural sales coming from a smaller percentage of existing farms. Farms today have a much larger output per person in comparison to the late 1800s. This has resulted in new food sources available to entire populations, which has had a large impact on the nutrition of society. Earliest forms of cooling The seasonal harvesting of snow and ice is an ancient practice estimated to have begun earlier than 1000 B.C. A Chinese collection of lyrics from this time period known as the Shih king, describes religious ceremonies for filling and emptying ice cellars. However, little is known about the construction of these ice cellars or what the ice was used for. The next ancient society to harvest ice may have been the Jews according to the book of Proverbs, which reads, “As the cold of snow in

Shri Technologies 5 Repair & Maintenance of Window & Split AC the time of harvest, so is a faithful messenger to them who sent him.” Historians have interpreted this to mean that the Jews used ice to cool beverages rather than to preserve food. Other ancient cultures such as the Greeks and the Romans dug large snow pits insulated with grass, chaff, or branches of trees as cold storage. Like the Jews, the Greeks and Rom and did not use ice and snow to preserve food, but primarily as a means to cool beverages. The Egyptians also developed methods to cool beverages, but in lieu of using ice to cool water, the Egyptians cooled water by putting boiling water in shallow earthen jars and placing them on the roofs of their houses at night. Slaves would moisten the outside of the jars and the resulting evapora- tion would cool the water. The ancient people of India used this same concept to produce ice. The Persians stored ice in a pit called a Yakhchal and may have been the first group of people to use cold storage to pre- serve food. In the Australian outback before a reliable electricity supply was available where the weather could be hot and dry, many farmers used a \"Coolgardie safe\". This consisted of a room with hessian \"curtains\" hanging from the ceiling soaked in water. The water would evaporate and thereby cool the hessi- an curtains and thereby the air circulating in the room. This would allow many perishables such as fruit butter and cured meats to be kept that would normally spoil in the heat. Ice harvesting Before 1830, few Americans used ice to refrigerate foods due to a lack of ice-storehouses and iceboxes. As these two things became more widely available, individuals used axes and saws to harvest ice for their storehouses. This method proved to be difficult, dangerous, and certainly did not resemble anything that could be duplicated on a commercial scale. Despite the difficulties of harvesting ice, Frederic Tudor thought that he could capitalize on this new com- modity by harvesting ice in New England and shipping it to the Caribbean islands as well as the southern states. In the beginning, Tudor lost thousands of dollars, but eventually turned a profit as he constructed icehouses in Charleston, Virginia and in the Cuban port town of Havana. These icehouses as well as better insulated ships helped reduce ice wastage from 66% to 8%. This efficiency gain influenced Tudor to expand his ice market to other towns with icehouses such as New Orleans and Savannah. This ice market further expanded as harvesting ice became faster and cheaper after one of Tudor’s suppliers, Nathaniel Wyeth, in- vented a horse-drawn ice cutter in 1825. This invention as well as Tudor’s success inspired others to get in- volved in the ice trade and the ice industry grew. Ice became a mass-market commodity by the early 1830s with the price of ice dropping from six cents per pound to a half of a cent per pound. In New York City, ice consumption increased from 12,000 tons in 1843

6 Shri TechnologiesShri Technologies to 100,000 tons in 1856. Boston’s consumption leapt from 6,000 tons to 85,000 tons during that same period. Ice harvesting created a “cooling culture” as majority of people used ice and iceboxes to store their dairy products, fish, meat, and even fruits and vegetables. These early cold storage practices paved the way for many Americans to accept the refrigeration technology that would soon take over the country. History: The basic concept behind air conditioning is said to have been applied in ancient Egypt, where reeds were hung in windows and were moistened with trickling water. The evaporation of water cooled the air blowing through the window. This process also made the air more humid, which can be beneficial in a dry desert climate. In Ancient Rome, water from aqueducts was circulated through the walls of certain hous- es to cool them. Other techniques in medieval Persia involved the use of cisterns and wind towers to cool buildings during the hot season. Modern air conditioning emerged from advances in chemistry during the 19th century, and the first large-scale electrical air conditioning was invented and used in 1902 by American inventor Willis Carrier. The introduction of residential air conditioning in the 1920s helped enable the great migration to the Sun Belt in the United States. Development of mechanical cooling The 2nd-century Chinese inventor Ding Huan (fl 180) of the Han Dynasty invented a rotary fan for air con- ditioning, with seven wheels 3 m (9.8 ft) in diameter and manually powered. In 747, Emperor Xuanzong (r. 712–762) of the Tang Dynasty (618–907) had the Cool Hall (Liang Tian) built in the imperial palace, which the Tang Yulin describes as having water-powered fan wheels for air conditioning as well as rising jet streams of water from fountains. During the subsequent Song Dynasty (960–1279), written sources men- tioned the air conditioning rotary fan as even more widely used. In the 17th century, Cornelis Drebbel demonstrated \"Turning Summer into Winter\" for James I of England by adding salt to water. In 1758, Benjamin Franklin and John Hadley, a chemistry professor at Cambridge University, conducted an experiment to explore the principle of evaporation as a means to rapidly cool an object. Franklin and Hadley confirmed that evaporation of highly volatile liquids (such as alcohol and ether) could be used to drive down the temperature of an object past the freezing point of water. They conducted their experiment with

Shri Technologies 7 Repair & Maintenance of Window & Split AC the bulb of a mercury thermometer as their object and with a bellows used to speed-up the evaporation. They lowered the temperature of the thermometer bulb down to −14 °C (7 °F) while the ambient tempera- ture was 18 °C (64 °F). Franklin noted that, soon after they passed the freezing point of water 0 °C (32 °F), a thin film of ice formed on the surface of the thermometer's bulb and that the ice mass was about a quarter- inch thick when they stopped the experiment upon reaching −14 °C (7 °F). Franklin concluded: \"From this experiment one may see the possibility of freezing a man to death on a warm summer's day\" In 1820, English scientist and inventor Michael Faraday discovered that compressing and liquefying am- monia could chill air when the liquefied ammonia was allowed to evaporate. In 1842, Florida physician John Gorrie used compressor technology to create ice, which he used to cool air for his patients in his hos- pital in Apalachicola, Florida. He hoped to eventually use his ice-making machine to regulate the tempera- ture of buildings. He even envisioned centralized air conditioning that could cool entire cities. Though his prototype leaked and performed irregularly, Gorrie was granted a patent in 1851 for his ice-making ma- chine. His hopes for its success vanished soon afterwards when his chief financial backer died; Gorrie did not get the money he needed to develop the machine. According to his biographer, Vivian M. Sherlock, he blamed the \"Ice King\", Frederic Tudor, for his failure, suspecting that Tudor had launched a smear cam- paign against his invention. Dr. Gorrie died impoverished in 1855, and the idea of air conditioning went away for 50 years. Since prehistoric times, snow and ice were used for cooling. The business of harvesting ice during winter and storing for use in summer became popular towards the late 19th century.This practice was replaced by mechanical ice-making machines. James Harrison's first mechanical ice-making machine began operation in 1851 on the banks of the Barwon River at Rocky Point in Geelong (Australia). His first commercial ice-making machine followed in 1854, and his patent for an ether vapor compression refrigeration system was granted in 1855. This novel system used a compressor to force the refrigeration gas to pass through a condenser, where it cooled down and liquefied. The liquefied gas then circulated through the refrigeration coils and vaporised again, cooling down the surrounding system. The machine employed a 5 m (16 ft.) flywheel and produced 3,000 kilo- grams (6,600 lb) of ice per day. Though Harrison had commercial success establishing a second ice company back in Sydney in 1860, he later entered the debate over how to compete against the American advantage of unrefrigerated beef sales to the United Kingdom. He wrote: \"Fresh meat frozen and packed as if for a voyage, so that the refrigerat-

8 Shri TechnologiesShri Technologies ing process may be continued for any required period\", and in 1873 prepared the sailing ship Norfolk for an experimental beef shipment to the United Kingdom. His choice of a cold room system instead of installing a refrigeration system upon the ship itself proved disastrous when the ice was consumed faster than ex- pected. Electromechanical cooling In 1902, the first modern electrical air conditioning unit was invented by Willis Carrier in Buffalo, New York. After graduating from Cornell University, Carrier found a job at the Buffalo Forge Company. While there, he began experimenting with air conditioning as a way to solve an application problem for the Sack- ett-Wilhelms Lithographing and Publishing Company in Brooklyn, New York. The first air conditioner, de- signed and built in Buffalo by Carrier, began working on 17 July 1902. Designed to improve manufacturing process control in a printing plant, Carrier's invention controlled not only temperature but also humidity. Carrier used his knowledge of the heating of objects with steam and reversed the process. Instead of sending air through hot coils, he sent it through cold coils (filled with cold water). The air was cooled, and thereby the amount of moisture in the air could be controlled, which in turn made the humidity in the room controllable. The controlled temperature and humidity helped maintain consistent paper dimensions and ink alignment. Later, Carrier's technology was applied to increase produc- tivity in the workplace, and The Carrier Air Conditioning Company of America was formed to meet rising demand. Over time, air conditioning came to be used to improve comfort in homes and automobiles as well. Residential sales expanded dramatically in the 1950s. In 1906, Stuart W. Cramer of Charlotte, North Carolina was exploring ways to add moisture to the air in his textile mill. Cramer coined the term \"air conditioning\", using it in a patent claim he filed that year as an ana- logue to \"water conditioning\", then a well-known process for making textiles easier to process. He com- bined moisture with ventilation to \"condition\" and change the air in the factories, controlling the humidity so necessary in textile plants. Willis Carrier adopted the term and incorporated it into the name of his com- pany. Shortly thereafter, the first private home to have air conditioning was built in Chapel Hill, North Carolina in 1933. Realizing that air conditioning would one day be a standard feature of private homes, particularly in regions with warmer climate, David St. Pierre DuBose (1898-1994) designed a network of ductwork and vents for his home Meadowmont, all disguised behind intricate and attractive Georgian-style open moldings.

9 This building is believed to be one of the first private homes in the United States equipped for central air conditioning. In 1945, Robert Sherman of Lynn, Massachusetts invented a portable, in-window air conditioner that cooled, heated, humidified, dehumidified, and filtered the air. The idea was subsequently stolen by a large manufacturer. Sherman did not have the resources to fight the big corporation in court and thus never re- ceived any money or recognition. He died in 1962. Refrigerant developmentShri Technologies The first air conditioners and refrigerators employed tox- Repair & Maintenance of Window & Split AC ic or flammable gases, such as ammonia, methyl chloride, or propane, that could result in fatal accidents when they leaked. Thomas Midgley, Jr. created the first non- flammable, non-toxic chlorofluorocarbon gas, Freon, in 1928. The name is a trademark name owned by DuPont for any Chlorofluorocarbon (CFC), Hydrochlorofluoro- carbon (HCFC), or Hydrofluorocarbon (HFC) refrigerant. The refrigerant names include a number indicating the molecular composition (e.g. R-11, R-12, R-22, R-134A). The blend most used in direct-expansion home and building comfort cooling is an HCFC known as R-22. R-12 was the most common blend used in automobiles in the US until 1994, when most designs changed to R-134A due to the ozone-depleting potential of R-12. R-11 and R-12 are no longer manufactured in the US for this type of application, so the only source for air-conditioning repair purposes is the cleaned and puri- fied gas recovered from other air conditioner systems. Several non-ozone-depleting refrigerants have been developed as alternatives, including R-410A. It was first commercially used by Carrier Corp. under the brand name Puron. Modern refrigerants have been developed to be more environmentally safe than many of the early chloro- fluorocarbon-based refrigerants used in the early- and mid-twentieth century. These include as HCFCs (R- 22, used in most U.S. homes even before 2011) and HFCs (R-134a, used in most cars) have replaced most CFC use. HCFCs, in turn, are supposed to have been in the process of being phased out under the Montreal Protocol and replaced by hydrofluorocarbons (HFCs) such as R-410A, which lack chlorine. HFCs, however, contribute to climate change problems. Moreover, policy and political influence by corporate executives

10 resisted change. Corporations insisted that no alternatives to HFCs existed. The environmental organiza- tion Greenpeace solicited a European laboratory to research an alternative ozone- and climate-safe refrig- erant in 1992, gained patent rights to a hydrocarbon mix of isopentane and isobutane, but then left the technology as open access. Their activist marketing first in Germany led to companies like Whirlpool, Bosch, and later LG and others to incorporate the technology throughout Europe, then Asia, although the corporate executives resisted in Latin America, so that it arrived in Argentina produced by a domestic firm in 2003, and then finally with giant Bosch's production in Brazil by 2004. In 1995, Germany made CFC refrigerators illegal. DuPont and other companies blocked the refrigerant in the U.S. with the U.S. E.P.A., disparaging the approach as \"that German technology.\" Questions 1. What is ice harvesting 2. What is mechanical Cooling 3. What is a refrigerant 4. Name a few refrigerants Shri TechnologiesShri Technologies

11 Industry Prospects for Refrigeration and Air Conditioning India officially classifies its population in 5 groups, based on annual household income (based on year 1995-96 indices). These groups are: Lower Income; Three subgroups of Middle Income; and Higher Income. Household income in the top 20 boom cities in India is projected to grow at 10 % annually over the next 8 years, which is likely to increase consumer spending on durables. With the emergence of concepts such as quick and easy loan, zero equated monthly instalment (EMI) charges, loan through credit card, loan over phone, it has become easy for Indian consumers to afford more expensive consumer goods. Overview of India’s Consumer Durables Market The Indian Consumer Durables segment can be segmented into 3 groups: White Goods Brown Goods Consumer Goods · Air conditioners · Microwave Ovens · TVs Repair & Maintenance of Window & Split AC · Refrigerators · Cooking Range · Audio and video systems · Washing Machines · Chimneys · Electronic accessories · Sewing Machines · Mixers · PCs · Watches and clocks · Grinders · Mobile phones · Cleaning equipment · Electronic fans · Digital cameras · Other domestic appliances · Irons · DVDs · CamcordersShri Technologies Products like air conditioners are no longer perceived as luxury products. The digital revolution is shaking up the consumer durables industry. With the advent of MP3 music files, personal video recorders, game machines, digital cameras, appliances with embedded devices, and a host of other media and services, it is no longer clear who controls which part of home entertainment. This has set off a battle for dominance, and the shakeup is spanning the entire technology spectrum. Industries According to Census data, approximately 69% of refrigeration and air conditioning mechanics worked in the construction industry, almost all for building equipment contractors (67%). A significant number were also employed in manufacturing (10%), repair and maintenance (5%) and wholesale trade (5%).

12 Questions What are white goods What are consumer goods What are brown goods Shri TechnologiesShri Technologies

13 Career Prospects for Refrigeration and Air ConditioningShri Technologies Refrigeration and air conditioning is vital in today's world, it is used in everything from manufacturing to Repair & Maintenance of Window & Split AC medicine, and this vast technology needs technicians/engineers to develop, research and repair it. Here are just a few reasons why you should consider joining the highly skilled work force employed in this ever evolving industry.  This is an interesting place to be as environmental and technical developments are driving the industry to change  Jobs in this industry will never be dull or unchallenging, you will meet new people and new problems with every new job or project  Throughout your working life you will learn new techniques and practices, continually improving your knowledge and skills  Your job will give you a sense of achievement- you could be designing, installing or fixing massive sys- tems worth many thousands of pounds There is a shortage of skilled engineers so most employers will invest in you, your training and your future There are many benefits that come with being a Split or Window AC Mechanic/Engineer  The potential to earn a good salary  Structured training and development leading to recognised qualifications  A skill that is always in demand and that can be used around the world  Good career prospects  Real job satisfaction You can have a rewarding career where no two days are the same The different nomenclatures for a Split or Window AC Mechanic/Engineer are:  Central air conditioning mechanic  Commercial air conditioning mechanic  Heating and cooling mechanic  Heating, ventilation and air conditioning (HVAC) mechanic  Refrigeration and air conditioning mechanic apprentice  Refrigeration mechanic  Transport refrigeration mechanic

14 Shri Technologies Sources of Employment Employment opportunities will arise primarily from positions left vacant by refrigeration and air condi- tioning mechanics who retire, and from employment increase. Other opportunities will also result from positions left vacant by mechanics promoted to contractor and foreman/woman, refrigeration and air con- ditioning mechanic positions or, for those with the required skills, construction manager positions Employment Opportunities: Technical and repair jobs remain stable for the past years, and until now the demand for technicians are still enormous. Aside from the Middle East countries, Australia are also open for A/C technician, they are offering high compensation package plus benefits for successful applicants. Work Environment: A/C Technician often works for repair stores; they often visit clients and often do repairs in their clients place. A/C technician are provided with safety suit and mask to avoid accidents and contact with heat or chemicals. Work Hours: The working time of A/C Technician may vary on the type of damage that they need to repair. They usual- ly work for 4-6 hours. Career Advancement: Entry level A/C Technician with a good performance record and experience can be promoted as Senior Technician. Questions 1. What are the career prospects of a A/c Mechanic 2. How does a career advancement happen for a A/c Mechanic 3. What is the working environment for A/c MechanicShri Technologies

15 Skills required for Split or Window AC Mechanic Employers are looking for candidates with technical knowledge of the trade, manual dexterity and a good sense of observation. Teamwork skills, the ability to analyse and solve problems, attention to detail and initiative are the main qualifications sought by employers. Bilingualism is sometimes required. Skills, interests and qualities As a Split or Window AC Mechanic / Engineer, you'll need:Shri Technologies  Good practical and hand skills Repair & Maintenance of Window & Split AC  The ability to follow technical drawings, building plans and other instructions  A careful and methodical approach to work  The ability to make accurate measurements  A head for heights and be prepared to work in all sorts of weather  A willingness to work in confined spaces  A presentable and pleasant manner  Good written and verbal communication skills  Good team working skills and the ability to work on your own initiative  A willingness to adapt to change  Good problem-solving skills. Nature of Job:  Air-conditioning and Cooler Technician or A/C Technician is responsible in conducting maintenance check and repairs for air-con and other cooling or heating system. Basic Tasks:  Conduct maintenance check for air-con, heaters and coolers  Install Air-con and heaters.  Repair damage and dysfunctional air-con, heaters and coolers  Check its functions and status  Fix and check backage type and Split type

16 Shri TechnologiesShri Technologies  Encode the reported damage of the air-con, heaters or cooler  Check the its major parts (i.e. Freon)  Conduct daily routine for inspections  Check leakage  Must have wide knowledge and skills in repairing different kinds of Air-Cons and Cooling, heating systems  Must have knowledge in trouble shooting  Ability to detect damages and malfunctions  Must have wide knowledge in backage and Split type for installation of window and Split Ac’s  Know how to change spare parts  Must have good communication skills As field experience increases, earning potential can increase. Employment opportunities are best in parts of the country that are experiencing population growth. This means more construction of new homes, apartments, and businesses that will require installation and continued service repairs on refrigeration systems and equipment. Skill set required: Repairing — Repairing machines or systems using the needed tools. Equipment Maintenance — Performing routine maintenance on equipment and determining when and what kind of maintenance is needed. Operation Monitoring — Watching gauges, dials, or other indicators to make sure a machine is working properly. Troubleshooting — Determining causes of operating errors and deciding what to do about it. Installation — Installing equipment, machines, wiring, or programs to meet specifications. Critical Thinking — Using logic and reasoning to identify the strengths and weaknesses of alternative so- lutions, conclusions or approaches to problems. Operation and Control — Controlling operations of equipment or systems. Equipment Selection — Determining the kind of tools and equipment needed to do a job. Quality Control Analysis — Conducting tests and inspections of products, services, or processes to evalu- ate quality or performance. Complex Problem Solving — Identifying complex problems and reviewing related information to develop and evaluate options and implement solutions.

17 Questions 1. What are the skills to be possessed by a AC mechanic 2. What are the abilities required by A/c Mechanic 3. What is the nature of job to be done by A/c MechanicShri Technologies Repair & Maintenance of Window & Split AC

18 Shri TechnologiesShri Technologies Common, Measuring and special Tools in Air Conditioning works. Refrigeration tools are used in performing preventive maintenance and repair on air conditioners, refrig- erators, freezers, and automotive air conditioner. They are as follows: Tube Cutter – is a refrigeration tool use to cut copper tubing from sizes 1/8” to 1/2” outside diameter. A larger tube cutter is also available for large tube diameters. Tubes are mark first before cutting. Slight pressure is applied to the copper tube during cutting. The burr inside the tube is cleaned with blade reamer. Flaring Tool – is a refrigeration tool use to spread the copper end outward until a flare is formed. File and ream the copper tube before flaring. The copper tube is inserted into the flaring block with 30% of its diameter protruding. Turn the flaring yoke slowly until the flare is completed. Remove copper tube and inspect for defects. Swagging Tool – is a refrigeration tool use to expand the inside diameter of a copper tube so that the resulting diameter is the same as the outside diameter. It is used to join two copper tubes of the same diameter. Clamp the copper tube by the flaring block so that an 'equal to the outside diameter' of the copper tube length is to be swagged. Brazing Torch – is a refrigeration tool use in soldering the joints of two copper tubes together. 800 degrees Fahrenheit is required to solder copper tubing. Map gas is general- ly used in these application, although oxygen-acetylene is also popular except they are bulky and heavy. It can reach a temperature of 3600 degrees Fahrenheit. When brazing copper tube joints, do it in a well ventilated area. Prolong inhalation can cause cancer. Copper Tube Bender – is a copper tube bending refrigeration tool. It has a three-size molded half-round wheels. The most common sizes are from 1/4 of an inch diameter, to 5/16, then 3/8. Copper tubes are bent beautifully using this professional bending tool. Adjustable wrench – is a wrench with an adjustable jaw. A six inch adjustable wrench

19Shri Technologies is very useful in the field of refrigeration repair. It can accommodate nuts and bolts' sizes Repair & Maintenance of Window & Split AC from 1/8 of an inch to 1 inch. It can fit into the tool box easily. Flat Edge Screw Driver – is a screw driver with a flat driving end. An 8 inch screw driver with a blade width of 1/4\" is the most useful size. It is always a good idea to have a 1/8\" blade and a 3/16\" blade around with you. Philip Screw Driver – is a screw driver with a cross driving end. It is a good idea to have three sizes of this type also. Buy only good quality philip screw driver because the teeth easily become blunt very slippery. Allen Wrench – is an angle hexagonal driving wrench. They are made of hardened steel. You will need allen key when removing the squirrel caged fan of a window type air con- ditioner. The circular fan of an indoor unit is fastened with an allen screw. Long Nose Plier – is a plier with a long pointed nose. A 7 inch long nose plier is very use- ful and is a good addition to your tool box. You will find the many uses of a long nose plier; from hard to-reach areas like removing a clip from a fan or holding the copper tube when brazing alone. Slip Joint Plier – is a mechanical plier with a slip joint in order to adjust the size. Either for fastening a 1/2\" pipe to loosening a 1\" water pipe, it is a very handy tool to have. I have with me a 10\" slip joint plier all the time. Electrical Plier – Insulated plier use by electrician. An 8 inch electrical plier is a must have in your tool box. There are time when it is necessary to remove a live fuse from a fuse box. Or arranging the stranded wires. Pipe Wrench – is a wrench for fastening tubes and pipes. A 12 in pipe wrench must be in your tool box as well. Sometimes we have to remove a rounded hex nut. Socket Wrench set – wrench with driving socket. We have the 1/2\" drive and the 3/8\" drive and the 1/4\" drive. I carry all of them when I am on the field. You will

20 Shri TechnologiesShri Technologies need a socket wrench to remove a remote hex nut or bolt where you have to add exten- sion just to remove it. The set come with a ratchet which is also a very handy tool. Nut Drivers – Hand held driver to drive or remove hex nuts or bolts. Mostly applicable to deep down places where our hand is not able to reach. Straight hand grip type and the T-type drivers are available for you to choose. Box Wrench – Hand held box type wrenches. They came in from 1/4 of an inch to 1- 1/4 inch size. Usually they are in combination as far as the size is concern. A practical tool for assembling and disassembling home air conditioner and automotive air condi- tioner compressors. Open Wrench – Open end hand held wrench. Their sizes are from 1/8 of an inch to 1- 1/4 of an inch. It is most useful when you are removing a machine bolt where access is only 50 to 75 percent, or the area is restricted that the wrench can make only one half turn. Flat File – flat hardened steel with cutting ridges. Used for filing a newly cut copper tube ends to square it. Or to remove burrs from steel brackets. File surface joints so that they can fit squarely. Round File – round long hardened steel with cutting ridges. Round file is very useful in enlarging a hole by filing. Cleaning a rusty steel tube, removing a clogged from a drain hole. Enlarging a flat washer hole to fit the larger bolt. Or to shape a certain parts through filing. Making prototype spare parts for hard-to-find spare. Half Round Files – Half round shaped long hardened steel with cutting ridges. When it is necessary to make a hole larger where the application of a round file is not practical. The half round side can finish a curve surface, and the flat side for the flat surface. Carpenter’s Saw – a hand tool with tooth blade used to cut wood. Fabricating wooden frame for a window type air conditioner, cutting wooden sticks to be used to elevate an air condi-

21 tioner unit. Fabricating elevated stand for a split type stand alone indoor unit. Tape measure – steel tape measuring device. Put one in your pocket whenever you are going out into the field. Either you are going to make measurement for the length of the copper tubing you will need for a certain project, or measuring the volume of a room.Shri Technologies Hack Saw – a hand tool with tooth blade used to cut iron pipes or iron bars, maybe you Repair & Maintenance of Window & Split AC need to shorten the length of a certain PVC pipe, or fabricating a bracket for a new air conditioner. Making a new home air conditioner installation. Cutting the window frame so that the new air conditioner will fit. Electric Drill Gun – is also a good refrigeration tool a refrigeration mechanic should have. We measure the size of a drill gun by the size of the chuck. I have with me a 1/2 inch chuck, and it is all I need in doing different things, like installing a new compressor and I need to make new holes for the anchor bolts. Bench Vise – a refrigeration tool with two jaws for holding works. Most of the time we need a vise to hold the copper tube so that we can braze the joints correctly. Or we must clamp the machine bolt so that we can remove the hex nut. Or simply clamp a piece of steel bar so that we can cut it into the size we need. Yoke Vise – a pipe vise. It is good to have a yoke vise in your working bench. Yoke vise is a common refrigeration tool a mechanic should have. Either you are lengthening your water pipes or removing electrical conduit pipes, a yoke vise clamps the tubing without deforming them. Pinching Tool: Pneumatic Ball Crimp Tools will pinch and seal soft copper tubing up to 3/8\" diameter. These tools will pinch and seal tubing so the technician can cut and seal the tubing with a solder or braze operation. This is a popular tool for the re- frigeration manufacturing industries. Snip Tool: A light weight, general purpose, special alloy hardened and tem- pered cutting blade. Comfort grip with spring action It Is used to cut metal

22 Shri TechnologiesShri Technologies Soldering Iron: A soldering iron is a hand tool used in soldering. It supplies heat to melt solder so that it can flow into the joint between two workpieces. A soldering iron is composed of a heated metal tip and an insulated handle. Heating is often achieved elec- trically, by passing an electric current (supplied through an electrical cord or battery cables) through a re- sistive heating element. Cordless irons can be heated by combustion of gas stored in a small tank, often using a catalytic heater rather than a flame. Sim- ple irons less commonly used than in the past were simply a large copper bit on a handle, heated in a flame. Soldering irons are most often used for installation, repairs, and limited pro- duction work in electronics assembly. High-volume production lines use other soldering methods Bench Vice: A fixture's primary purpose is to create a secure mounting point for a work piece, allowing for support during operation and increased accuracy, precision, reliability, and interchangeability in the fin- ished parts. It also serves to reduce working time by allowing quick set -up, and by smoothing the transi- tion from part to part. It frequently reduces the complexity of a process, allowing for unskilled workers to perform it and effectively transferring the skill of the tool maker to the un- skilled worker. Fixtures also allow for a higher degree of operator safety by reducing the concentration and effort required to hold a piece steady. A hammer is a tool that delivers a blow (a sudden impact) to an object. The most common uses for hammers are to drive nails, fit parts, forge metal, and break apart objects. Hammers vary in shape, size, and structure, de- pending on their uses. Hammers are basic tools in many trades. The usual features are a head (most often made of steel) and a handle (also called a helve or haft). Most hammers are hand tools, but there are also many powered versions—power hammers (also called steam hammers or trip hammers, depending on design)—for heavier uses The halide leak detector works on the principle of change of colour of a flame in the presence of the refrigerants. When a fluorocarbon based refrigerant such as R12 or R22 is sucked through a sampling tube and passed over a surface whose surface temperature is high

23 Repair & Maintenance of Window & Split AC (around 500oC), then the refrigerant vapour breaks down and forms a foul smelling gas known as phosgene (COCl2). When this gas is passed over a glowing copper (heated by the flame of the torch itself) it forms copper chloride, which changes the colour of the flame from pale blue to bright green. The halide torch usually burns methyl alcohol, butane gas or acetylene and is similar in construction to that of a blow lamp with a provision to draw the air for combustion through a sampling tube. If the air consists of refrigerant (due to leakage) then it is detected by the change in the colour of the flame. Using halide leak detectors leaks as small as 1.5 to 2 oz. Per year could be detected. However, use of halide leak detectors requires certain precautions to be taken while using. It cannot be used with hydrocarbon refrigerants. Double end Spanner Set: These are used to tighten or loosen the bolts of the ma- chine. They are available for different screw sizes. Nitrogen Cylinder: Nitrogen (oxygen free / OFN) is the most commonly used gas to pressure test systems prior to refrigerant charge, or as part of ser- vicing following refrigerant recovery. Vaccum Pump: The purpose of a vacuum pump is to remove moisture and air from an A/C-R system. Modern systems are built tighter and charges are more critical. That means these sys- tems have a greater sensitivity to moisture and other contaminants, making thorough evacua- tion more important than ever before. Questions List some of the tools that are used by AC MechanicShri Technologies

24 Shri TechnologiesShri Technologies Common Terminology Air-cooled system: A type of precision cooling system widely used in IT environments of all sizes. In an air- cooled system the condensing coil is exposed directly to the outside atmosphere. All other refrigeration cy- cle components are contained within the air conditioner. This sometimes requires refrigerant lines to be run long distances to the building’s roof or external perimeter. BTU: The abbreviation for British thermal unit. A measurement of heat energy commonly used to measure heat loads in data centres and IT rooms in North America. A BTU is defined as the amount of heat energy required to raise the temperature of one pound of water by one degree Fahrenheit in one hour. This is an archaic term typically used to specify heat output when expressed in BTU/Hr, where the use of the term Watts is the simpler and more universal measure. Ceiling mount: A small precision air conditioner hung from, or suspended above, a ceiling. This type of air conditioner comes in many designs, but usually is connected to a heat rejection unit on an outdoor pad or rooftop via refrigerant or water lines Compressor: The compressor is an essential component in the refrigeration cycle that uses mechanical ener- gy to compress or squeeze gaseous refrigerant. This compression process is what allows an air conditioner to absorb heat at one temperature (like 70°F / 21°C) and exhaust it outdoors at a potentially higher temper- ature (like 100°F / 38°C) Condenser coil: A condenser coil is one means of heat rejection commonly used in an air conditioning sys- tem. It is typically located on an outdoor pad or on a rooftop and looks like an automobile radiator in a cabi- net. It is usually hot to the touch (120°F / 49°C) during normal use. Its function is to transfer heat energy from the refrigerant to the cooler surrounding (usually outdoor) environment. The related Dry Cooler or Fluid Cooler serves the same purpose of heat rejection and physically appears similar, with the difference that the condenser coil uses hot refrigerant which changes from a gas to liquid as it move through the coil, whereas the Fluid Cooler uses hot liquid such as water or a water-glycol mix Dehumidification: The process of removing moisture from air. In the data center or IT room, most dehu- midification occurs as moisture-laden air flows across the cold evaporator coil. I basic example of the dehu- midification process is when a cold soda can is left outdoors. The water moisture in the air is removed by

25 condensing on the surface of the can as water droplets. Evaporator coil: The evaporator coil is an essential component used in the refrigeration cycle. It looks like an automobile radiator. This is the part of the system that gets cold to the touch (about 45°F / 7°C for air conditioning systems) during normal use. Its usually found inside the space we need to remove heat from. Cold-feeling air that exits an air conditioner has just transferred some heat energy to the flashing refrigerant as it passed through the evaporator coil. Expansion valve: The expansion valve is an essential component used in the refrigeration cycle. It regu- lates the flow of high-pressure liquid refrigerant into the evaporator coil. It is designed to open just enough to let refrigerant flow while maintaining a high pressure differential from its inlet to its outlet. The pressure at the exit of the expansion valve is low enough that it initiates a phase change in the liquid refrigerant to a vapor. A pressurized spray can is an example of how an expansion value works. If you spray a can of butane fuel for a few seconds, the can will become colder as the pressure inside decreases. Psychometric chart: The properties of air and the water contained in it at different temperatures arranged in the form of a chart. In particular it shows the quantitative interdependence between temperature and humidity. It is useful in the planning, specification and monitoring of cooling systems. Refrigerant Repair & Maintenance of Window & Split AC The working fluid used in the refrigeration cycle is known as the refrigerant. Modern systems primarily use fluorinated hydrocarbons that are non-flammable, non-corrosive, nontoxic, and non-explosive. Re- frigerants are commonly referred to by their ASHRAE numerical designation. The most commonly used refrigerant in the IT environment is R-22. Environmental concerns of ozone depletion may lead to legisla- tion increasing or requiring the use of alternate refrigerants like R-134a. Questions 1. What is BTU 2. What is a compressorShri Technologies

26 Shri TechnologiesShri Technologies Equipment’s and Meters in R&AC trade Tong Tester: In electrical and electronic engineering, a current clamp or current probe is an electrical device having two jaws which open to allow clamping around an elec- trical conductor. This allows properties of the electric current in the conductor to be measured, without having to make physical contact with it, or to disconnect it for in- sertion through the probe. Current clamps are usually used to read the magnitude of a sinusoidal current (as invariably used in alternating current (AC) power distribu- tion systems), but in conjunction with more advanced instrumentation the phase and waveform are availa- ble. Very high alternating currents (1000 A and more) are easily read with an appropriate meter; direct cur- rents, and very low AC currents (milliamperes) are more difficult to measure. Line Tester: voltage tester, or mains tester is a simple piece of electronic test equipment used to determine the presence or absence of an electric voltage in a piece of equipment under test. An ammeter is a measuring instrument used to measure the electric current in a circuit. Electric currents are measured in amperes (A), hence the name. Instruments used to measure smaller currents, in the milliampere or microampere range, are designated as milliammeters or microammeters. A multimeter or a multitester, also known as a VOM (Volt-Ohm meter or Volt -Ohm-milliammeter ), is an electronic measuring instrument that combines sev- eral measurement functions in one unit. A typical multimeter would include basic features such as the abil- ity to measure voltage, current, and resistance. Analog multimeters use a microammeter whose pointer moves over a scale calibrated for all the different measurements that can be made. Digital multimeters (DMM, DVOM) display the measured value in numerals, and may also display a bar of a length propor- tional to the quantity being measured. Digital multimeters are now far more common but analog multime- ters are still preferable in some cases, for example when monitoring a rapidly varying value. A voltmeter is an instrument used for measuring electrical potential difference between two points in an

27 electric circuit. Analog voltmeters move a pointer across a scale in proportion to the voltage of the circuit; digital voltmeters give a numerical display of voltage by use of an analog to digital converter. Gauge Manifold – refrigeration tool pressure gauges. Whenever you are reprocessing a refrigerator, or replacing a new compressor for a freezer, or charging refrigerant to your automotive air conditioner, you need a gauge manifold to tell you if you are doing it right. Pressure Gauge: A vacuum gauge is used to measure the pressure in a vacuum—which is further divided into two subcategories, high and low vacuum (and sometimes ultra-high vacuum). The applicable pressure range of many of the techniques used to measure vacu- ums have an overlap. Hence, by combining several different types of gauge, it is possible to measure system pressure continuously from 10 mbar down to 10−11 mbar. Questions What is a line tester What is an ammeter What is Manifold What is the purpose of a pressure gaugeShri Technologies Repair & Maintenance of Window & Split AC

28 Shri TechnologiesShri Technologies Heat and related terms Heat transfer between two bodies, two materials, or two regions is the result of temperature difference. The science of heat transfer has provided calculations and analyses to predict rates of heat transfer. The design of an air conditioning system must include estimates of heat transfer between the conditioned space, its contents, and its surroundings, to determine cooling and heating loads. Heat-transfer analysis can be described in three modes: 1. Conduction: Conduction is the mechanism of heat transfer in opaque solid media, such as through walls and roofs. 2. Convection: Convective heat transfer occurs when a fluid comes in contact with a surface at a different temperature, such as the heat transfer taking place between the airstream in a duct and the duct wall. Con- vective heat transfer can be divided into two types: forced convection and natural or free convection. When a fluid is forced to move along the surface by an outside motive force, heat is transferred by forced convec- tion. When the motion of the fluid is caused by the density difference of the two streams in the fluid as a product of contacting a surface at a different temperature, the result is called natural or free convection. 3. Radiation: In radiant heat transfer, heat is transported in the form of electromagnetic waves traveling at the speed of light. Some terms: Heat Capacity: The heat capacity (HC) per square foot (meter) of an element or component of a building envelope or other structure depends on its mass and specific heat. Heat Transfer Co-efficient: Determination of heat-transfer coefficients to be used for load calculations or year-round energy estimates is complicated by the following types of variables:  Building envelopes, exterior wall, roof, glass, partition wall, ceiling, or floor  Fluid flow, turbulent flow, or laminar flow, forced or free convection  Heat flow, horizontal heat flow in a vertical surface, or an upward or downward heat flow in a hori- zontal surface  Space air diffusion, ceiling or sidewall inlet, or others  Time of operation—summer, winter, or other seasons

Shri Technologies 29 Repair & Maintenance of Window & Split AC Among the three modes of heat transfer, convection processes and their related coefficients are the least un- derstood, making analysis difficult. Moisture Transfer: Moisture is water in the vapor, liquid, and solid states. Building materials exposed to excessive moisture may degrade or deteriorate as a result of physical changes, chemical changes, and bio- logical processes. Moisture accumulated inside the insulating layer also increases the rate of heat transfer through the building envelope. Moisture transfer between the building envelope and the conditioned space air has a significant influence on the cooling load calculations in areas with hot and humid climates. Moisture Migration in Building Materials: Building envelopes are not constructed only with open-cell ma- terials. The airstream and its associated water vapor cannot penetrate building envelopes. Air leakage can only squeeze through the cracks and gaps around windows and joints. However, all building materials are moisture permeable; in other words, moisture can migrate across a building envelope because of differences in moisture content or other driving potentials. CONDENSATION IN BUILDINGS: When moist air contacts a solid surface whose temperature is lower than the dew point of the moist air, condensation occurs on the surface in the form of liquid water, or some- times frost. Condensation can damage the surface finish, deteriorate the material and cause objectionable odors, stains, corrosion, and mold growth; reduce the quality of the building envelope with dripping water; and fog windows. Two types of condensation predominate in buildings: 1. Visible surface condensation on the interior surfaces of external window glass, below-grade walls, floor slabs on grade, and cold surfaces of inside equipment and pipes 2. Concealed condensation within the building envelope THERMAL INSULATION: Thermal insulation materials, usually in the form of boards, slabs, blocks, films, or blankets, retard the rate of heat transfer in conductive, convective, and radiant transfer modes. They are used within building envelopes or applied over the surfaces of equipment, piping, or ductwork to achieve the following benefits: 1. Savings of energy by reducing heat loss and heat gain from the surroundings 2. Prevention of surface condensation by increasing the surface temperature above the dew point of the ambient air 3. Reduction of temperature difference between the inside surface and the space air for the thermal com- fort of the occupants, when radiant heating or cooling is not desired

30 Shri TechnologiesShri Technologies 4.Protection of the occupant from injury due to contact with hot pipes and equipment Basic Materials and Thermal Properties: Basic materials in the manufacture of thermal insulation for building envelopes or air conditioning systems include  Fibrous materials such as glass fiber, mineral wool, wood, cane, or other vegetable fibers  Cellular materials such as cellular glass, foam rubber, polystyrene, and polyurethane  Metallic reflective membranes Types of Window Glass (Glazing): Most window glasses, or glazing, are vitreous silicate consisting of sili- con dioxide, sodium oxide, calcium oxide, and sodium carbonate. They can be classified as follows:  Clear plate or sheet glass or plastic. Clear plate glass permits good visibility and transmits more solar radiation than other types.  Tinted heat-absorbing glass. Tinted heat-absorbing glass is fabricated by adding small amounts of sele- nium, nickel, iron, or tin oxides. These produce colors from pink to green, including gray or bluish green, all of which absorb infrared solar heat and release a portion of this to the outside atmosphere through outer surface convection and radiation. Heat-absorbing glass also reduces visible light trans- mission.  Insulating glass. Insulating glass consists of two panes—an outer plate and a inner plate—or three panes separated by metal, foam, or rubber spacers around the edges and hermetically sealed in a stain- less-steel or aluminum-alloy structure. The dehydrated space between the glass panes usually has a thickness of 0.125 to 0.75 in. (3.2–19 mm) and is filled with air, argon, or other inert gas. Air- or gas- filled space increases the thermal resistance of the fenestration.  Reflective coated glass. Reflective glass has a microscopically thin layer of metallic or ceramic coating on one surface of the glass, usually the inner surface of a single-pane glazing or the outer surface of the inner plate for an insulating glass. For a single pane, the coating is often protected by a layer of trans- parent polyester. The chromium and other metallic coatings give excellent reflectivity in the infrared regions but reduced transmission of visible light compared to clear plate and heat-absorbing glass. Re- flections from buildings with highly reflective glass may blind drivers, or even kill grass in neighboring yards.

31  Low-emissivity (low-E) glass coatings. Glazing coated with low-emissivity, or low-E, films has been in use since 1978. It is widely used in retrofit applications. A low-emissivity film is usually a vacuum- deposited metallic coating, usually aluminum, on a polyester film, at a thickness of about 4 _ 10_7 in. (0.01 m). Because of the fragility of the metal coating, protection by another polyester film against abra- sion and chemical corrosion must be provided. Questions 1. What is thermal insulation? 2. What is Window Glazing? 3. What is condensation in buildings?Shri Technologies Repair & Maintenance of Window & Split AC

32 Shri TechnologiesShri Technologies Temperature and related terms Heat and Temperature Heat energy is most intense in substances whose molecules are moving rapidly in a very disorderly way. Such a substance will give up some of its heat to another substance whose molecules are less agitated. When this happens, the heat is said to “flow” from one substance to another (or from one body to another). The energy transfer is indicated by a change in temperature. Temperature, therefore, is not the same thing as heat—although the two words are often used interchange- ably. Temperature can be defined as the degree of intensity of hotness or coldness. “Hotness” and “coldness,” however, are comparative terms. A flame, for example, is hot when compared with ice but cold when compared with the sun. This definition of temperature, therefore, is vague and unscientific, although it does convey the correct impression that temperature is a measure of relative intensity rather than of quantity. A more specific definition is: temperature is the ability of one body to give up heat energy to another body. A hot body becomes cooler, and a cold body becomes warmer, as long as heat is flowing from one to the other. The hot body has a greater ability to give up heat and therefore has a higher temperature. After a time the two bodies may reach a condition of heat equilibrium, or balance of heat intensity. Then, heat flow ceases. At the point of equilibrium both bodies can be said to be at the same temperature. Measurement of Temperature Temperature is measured by means of instruments called thermometers. Several temperature scales have been devised for relating the hotness and coldness of bodies to fixed temperatures, such as the freezing point and boiling point of water. On most temperature scales, the unit of temperature is called a degree. The Kelvin scale is an exception; its unit of temperature is the kelvin. The Fahrenheit, Celsius (or centigrade), and Reaumur scales are used in the range of temperatures im- portant for human comfort, laboratory experiments, and industrial processes. The Rankine scale and the Kelvin scale are based on the concept of absolute zero; all temperature readings on these scales are positive numbers. The Kelvin scale is widely used in scientific work. The Rankine scale is used primarily by British and American engineers. Absolute Zero Experiments have shown that every 1° C. increase or decrease in temperature causes the pressure exerted by a gas to increase or decrease at the constant rate of 1/273.15 of its pressure at 0° C. This means that at - 273.15° C. an ideal (theoretical) gas would exert no pressure at all. Since experiments with real gases have shown a clear relation between pressure and temperature, zero pressure would indicate that the ideal gas had lost all its ability to give up heat. Its molecules would be absolutely motionless. This is impossible— molecules are always agitated, to some extent—and therefore the absolute zero of temperature remains a theoretical concept. The concept is, however, a useful one, for it gives a base point to which all temperature measurements may be referred, in positive numbers. The idea that absolute zero can never be reached is sometimes considered important enough to be called the third law of thermodynamics. Scientists have succeeded in cooling substances to within a small fraction of a degree above absolute zero. The study of the behavior of substances at very low temperatures is called cryogenics.

33 High Temperatures Absolute zero is the lower limit for temperature, but there is no upper limit. The hottest substances known are ionized gases in certain stars, with temperatures of a billion degrees or more. Measurement of Heat The heat released or absorbed in a physical or chemical process can be measured with an instrument called a calorimeter. Commonly used units for measuring heat are the calorie and the British thermal unit, or Btu. Heat is also measured in such other units as the joule (the unit of energy in the SI, or metric system). Questions 1. What is absolute zero 2. What is Heat 3. How is temperature measuredShri Technologies Repair & Maintenance of Window & Split AC

34 Shri TechnologiesShri Technologies Refrigeration related Pressure Pressure (symbol: p or P) is the force applied perpendicular to the surface of an object per unit area over which that force is distributed Various units are used to express pressure. Some of these derive from a unit of force divided by a unit of area; the SI unit of pressure, the pascal (Pa), for example, is one newton per square metre; similarly, the pound-force per square inch (psi) is the traditional unit of pressure in the impe- rial and US customary systems. Pressure may also be expressed in terms of standard atmospheric pressure; the atmosphere (atm) is equal to this pressure and the torr is defined as 1⁄760 of this. Refrigerant Pressures The typical vapor compression refrigeration system (as shown in Figure 1) can be divided into two pres- sures. They are condensing and evaporating - or high- and low-side - pressures. These pressures are divid- ed or separated in the system by the compressor's discharge valve and the metering device. Listed below are field service terms or trade jargon often used to describe these pressures. Condensing pressure: High-side pressure, head pressure, discharge pressure. Evaporating pressure: Low-side pressure, suction pressure, back pressure Condensing Pressure The condensing pressure is the pressure at which the refrigerant is phase changing from a vapor to a liquid. This phase change is referred to as condensation. Thus the term condensing pressure. This pressure can be read directly from a pressure gauge connected anywhere between the compressor's discharge valve and the entrance to the metering device, assuming that there is negligible pressure drop. In reality, line and valve friction and the weight of the liquid itself cause pressure drops from the discharge of the compressor to the metering device. If a true condensing pressure is needed, the technician must measure the pressure as close to the condenser as possible to avoid these pressure drops. This pressure is usually measured on smaller systems near the compressor's valves. On these small systems, it is not critical where a technician places the pressure gauge as long as it is on the high side of the system because pressure drops are negligible.

Shri Technologies 35 Repair & Maintenance of Window & Split AC The pressure gauge will read the same no matter where it is on the high side of the system if line and valve losses are negligible. Evaporating Pressure The evaporating pressure is the pressure at which the refrigerant is phase changing from a liquid to a va- por. This phase change is referred to as evaporation or vaporizing, thus the term evaporating pressure. A pressure gauge placed anywhere between the metering device outlet and the compressor will read the evaporating pressure. Again, negligible pressure drops are assumed. In reality, there will be line and valve pressure drops as the refrigerant travels through the evaporator and suction line. So, the technician must measure the pressure as close to the evaporator as possible to get a true evaporating pressure. On small systems where pressure drops are negligible, this pressure is usually measured near the compres- sor. Again, on small systems, gauge placement is not critical as long as it is placed on the low side of the refrigeration system. This is because the refrigerant vapor pressure acts in all directions equally. However, line and valve pressure drops are assumed to be negligible in this simple system. If line and valve pressure becomes substantial, gauge placement becomes critical. The larger and more sophisticated the system, the more critical gauge placement becomes because of associated line and valve pressure losses. If the system has significant line and valve pressure losses, the technician must place the gauge as close as possible to the component that he wishes to read the pressure from. Refrigerant States Modern refrigerants exist in either the vapor or liquid states. Refrigerants have such a low freezing point that they are rarely in the frozen or solid state. Refrigerants can coexist as a vapor and liquid as long as con- ditions are right. Both the evaporator and condenser house liquid and vapor refrigerant simultaneously if the system is op- erating properly. So, refrigerant liquid and vapor can exist in either high- or low-pressure sides on the re- frigeration system.

36 Shri TechnologiesShri Technologies Refrigerant Conditions Along with refrigerant pressures and states, there are refrigerant conditions. Refrigerant conditions can be saturated, superheated, or subcooled. Saturated condition: Saturation is usually talked about in reference to a temperature. The saturation tem- perature is the temperature that a fluid will phase change from liquid to vapor or vapor to liquid. Both the liquid and vapor at their saturation temperatures are called saturated liquid and saturated vapor re- spectively. Saturation occurs in both the evaporator and condenser since phase changes experiencing both liquid and vapor are present here. At saturation, the liquid is experiencing its maximum temperature for that pres- sure, and the vapor is experiencing its minimum temperature for that pressure. However, both liquid and vapor are at the same temperature for a given pressure when saturation occurs. An exception to this would be some refrigerant blends. (As a reminder, this column is addressing refriger- ants that exist as pure compounds, such as R-134a.) Saturation temperatures vary with different refriger- ants and rely on the pressure that the refrigerant is exposed to. All refrigerants have different vapor pressures. It is vapor pressure that is measured with the technician's gauges. Vapor pressure is pressure exerted on a saturated liquid. Any time there is saturated liquid and vapor to- gether, as in the condenser and evaporator, there will be vapor pressure present. Vapor pressure acts equally in all directions and affects the entire low or high side of a refrigeration system. As pressure in- creases, saturation temperature increases. As pressure decreases, so does saturation temperature. In fact, only at saturation are there pressure-temperature relationships for refrigerants. Temperature- pressure charts (such as the one shown in Figure 2) show pressure and temperature relationships at satu- ration. In fact, if one attempts to raise the temperature of a saturated liquid above its saturation temperature, va- porization of the liquid will occur. If one attempts to lower the temperature of a saturated vapor below its saturation temperature, condensation will occur. Both vaporization and condensation occur in the evapo-

37 rator and condenser respectively. The heat energy that causes a liquid refrigerant to change to a vapor at a constant saturation temperature for a given pressure is referred to as a latent heat process. Latent heat is heat energy that causes a change in phase of a substance without a change in the temperature of the substance. Phase changes go from liquid to vapor, or from vapor to liquid. Vaporization and condensation are examples of a latent heat process. Both vaporization and condensation occur in the evaporator and condenser respectively. Superheated condition: Superheat always refers to a vapor. A superheated vapor is any vapor above its sat- uration temperature for a given pressure. In order for vapor to be superheated, it must have reached its 100 percent saturated vapor point. In other words, all of the liquid has to be vaporized for superheating to occur. The vapor must be removed from contact with the vaporizing liquid. Once all of the liquid has been vaporized at its saturation tempera- ture, any addition of heat will cause the 100 percent saturated vapor to start superheating. This addition of heat will cause the vapor to increase in temperature and gain sensible heat. Sensible heat is Repair & Maintenance of Window & Split AC heat energy that causes a change in the temperature of a substance. However, before a vapor can reach the superheat state, it must be physically removed from the vaporized liquid. Superheat vapor occurs in the evaporator's outlet, suction line, and compressor. The heat energy that superheats vapor and increases its temperature is referred to as sensible heat energy. Superheating is a sensible heat process.Shri Technologies Subcooled condition: Subcooling always refers to a liquid at a temperature below its saturation temperature for a given pressure. Once the entire vapor has phase changed to 100 percent saturated liquid during satura- tion, the further removal of heat will cause the 100 percent liquid to drop in temperature or lose sensible heat. Subcooled liquid is now formed. Subcooling can occur in both the condenser and liquid line and is a sensible heat process. Question What is refrigerant pressure

38 Shri Technologies Force, Work, Energy, Power Force: force is any interaction which tends to change the motion of an object. In other words, a force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate. Force can also be described by intuitive concepts such as a push or a pull. A force has both magnitude and direction, making it a vector quantity. It is measured in the SI unit of newtons and repre- sented by the symbol F. Work: Refers to an activity involving a force and movement in the direction of the force. A force of 20 new- tons pushing an object 5 meters in the direction of the force does 100 joules of work. Energy: is the capacity for doing work. You must have energy to accomplish work - it is like the \"currency\" for performing work. To do 100 joules of work, you must expend 100 joules of energy. Power: is the rate of doing work or the rate of using energy, which are numerically the same. If you do 100 joules of work in one second (using 100 joules of energy), the power is 100 watts. The same amount of work is done when carrying a load up a flight of stairs whether the person carrying it walks or runs, but more power is needed for running because the work is done in a shorter amount of time. The output power of an electric motor is the product of the torque that the motor generates and the angular velocity of its output shaft.Shri Technologies

39 Tube & Pipe and their fittings (Capillary Tube) Copper tubing is most often used for supply of hot and cold tap water, and as refrigerant line in HVAC sys- tems. There are two basic types of copper tubing, soft copper and rigid copper. Copper tubing is joined us- ing flare connection, compression connection, or solder. Copper offers a high level of corrosion resistance, but is becoming very costly. Copper tubing are to be checked on Chemical composition, Temper, Tolerance and Cleanliness, meeting the stringent 'CFC' and comply with the global standards. There are two types of Copper Tubing Soft copper Soft (or ductile) copper tubing can be bent easily to travel around obstacles in the path of the tubing. While the work hardening of the drawing process used to size the tubing makes the copper hard/rigid, it is care- fully annealed to make it soft again; it is therefore more expensive to produce than non-annealed, rigid cop- per tubing. It can be joined by any of the three methods used for rigid copper, and it is the only type of cop- per tubing suitable for flare connections. Soft copper is the most popular choice for refrigerant lines in split- system air conditioners and heat pumps. Rigid copper Repair & Maintenance of Window & Split AC Rigid copper is a popular choice for water lines. It is joined using a sweat, roll grooved, compression or crimped/pressed connection. Rigid copper, rigid due to the work hardening of the drawing process, cannot be bent and must use elbow fittings to go around corners or around obstacles. If heated and allowed to slowly cool in a process called annealing, rigid copper will become soft and can be bent/formed without cracking. Chemical Composition of a Cooper Tube:Shri Technologies Chemical Composition Phosphorus - 0.015 to 0.035 % DHP Copper Copper - Balance Phosphorus - 0.05 to 0.012 % DLP Copper Copper - Balance H, HH. 1/4 H, O (soft annealed ), TEMPER OL (Light annaealed)

40 CONNECTING TUBE COIL SETS FOR SPLIT ACS Outer Diameter 4.76 MM to 19.05 MM Length 5MTRS or as per customer's requirement Shri TechnologiesShri Technologies

41 Soldering, Brazing & Gas weldingShri Technologies Welding and Cutting Processes Repair & Maintenance of Window & Split AC Welding involves joining two or more pieces of metal together to form a single piece. Molten metal is gener- ated through an intense heat source, such as oxygen and fuel gas or an electrical arc. Common welding pro- cesses using an electrical arc include Shielded Metal Arc Welding, Gas Metal Arc Welding, and Gas Tung- sten Arc Welding. Unlike welding processes which join two pieces of metal, cutting processes involve separating or severing a piece of metal through intense heat generated to melt the metal. Cutting processes include oxygen and fuel gas and electrical arc gouging.  Gas Welding/Cutting Gas welding, or oxy/fuel welding as it is commonly referred to, is slower and easier to control than arc welding. This method unites metals by heating - the heat source being a flame produced by the combustion of a fuel gas, such as acetylene, methylacetylene (MAPP gas), or hydrogen. Temperatures can reach up to 6,000 deg. F. This process sometimes includes the use of pressure and a filler material. Gases commonly used are oxygen and either acetylene, hydrogen, propane, or propylene. These gases are commonly supplied in compressed gas cylinders, which can pose additional handling and transport hazards. For more infor- mation on the safe use, handling, and transport of compressed gas cylinders.  Arc Welding/Cutting In arc welding, the intense heat needed to melt metal is produced by an electric arc. The arc is formed be- tween the actual work piece and an electrode (stick or wire) that is manually or mechanically guided along the joint. The electrode can either be a rod, with the purpose of simply carrying the current between the tip and the work, or it may be a specially prepared rod or wire that not only conducts current, but also melts and supplies filler metal to the joint. Power sources for arc welding can be either alternating (AC) or direct (DC) current. The work cable connects to the work piece and the electrode cable creates an arc across the gap when the energized circuit and the electrode tip touches the workpiece and is withdrawn (yet still in close contact). The arc produces a temperature of about 6,500 deg. F at the tip. This heat melts both the base metal

42 Shri TechnologiesShri Technologies and the electrode, producing a pool of molten metal. Metals at high temperatures can react chemically with elements in the air (oxygen and nitrogen). Oxides and nitrides form, which destroy the strength of the weld. A protective shield of gas, vapor, or slag is used to cover the arc and molten pool to prevent or mini- mize contact or molten metal with air.  Shielded Metal Arc Welding Shielded Metal Arc Welding (SMAW) is commonly known as \"stick\" welding. A flux-covered electrode is used to form a gas shield around the molten weld pool. The flux coating quickly forms a protective \"slag\" during welding, which produces a gas shield that decreases exposure to oxygen. The electrode is con- sumed as it moves down the length of the weld joint and the \"slag\" must cool and later be chipped away.  Gas Metal Arc Welding Gas Metal Arc Welding (GMAW) is commonly known as \"MIG\" welding. A continuous-feed electrode (i.e. wire) from a spool is used to supply filler metal directly from the torch tip to the weld. As arcing occurs, the electrode instantly melts and a shielding gas, such as argon, carbon dioxide, or helium, is supplied through the torch tip.  Gas Tungsten Arc Welding Gas Tungsten Arc Welding (GTAW) is commonly known as \"TIG\" welding. An electric arc between a tungsten electrode and the base metal is created. A separate filler rod is fed into the molten base metal, if needed. A shielding gas (i.e. commonly argon, helium, or carbon dioxide) also flows around the arc to minimize atmospheric interactions. Water is often used to cool the torch and cables.  Plasma Arc Welding Plasma Arc Welding (PAW) is similar to TIG welding in which an arc, shielded by an inert gas, creates the necessary heat to melt the metals involved. The electrode is not consumed in PAW; however, the primary means of transfering heat to the workpiece is by a hot ionized gas (i.e. \"plasma\"). Temperatures can reach up to 30,000 deg. F, which is substantially hotter than those produced by an arc only. Commonly, PAW is a fully automatic process. Filler metal may be used, and plasma and shielding gases include argon, argon/ helium, and argon/hydrogen.

43 Repair & Maintenance of Window & Split AC  Brazing Brazing is a process similar to welding in that a liquid filler metal is heated and flows between two or more metal surfaces to be joined. It is very flexible in that any number of metals may be joined. However, brazing occurs at lower temperatures than welding, typically around 840 deg. F. A braze metal is heated to a liqui- fied state and is spread over the surface to be joined, rather than both the base metal and filler metal being heated to a molten state as in welding. Parts to be joined must be very clean, often using mechanical meth- ods such as sanding, grinding, abrasive blasting, or the use of chemical solvents. There are several types of brazing based upon the source of heat. Brazing is commonly used to seal or join pipes and the associated hazards are similar to those of welding. Reviewing Material Safety Data Sheets for the metals, cleaning agents, fluxes, and filler metals is very important in identifying associated health hazards and implementing appropriate hazard controls. Soldering Soldering is similar to welding in that both the base metal and the filler metals are heated to melting and then solidify to form a joint; however, soldering temperatures are typically 840 deg. F or less. Soldering typi- cally involves smaller components to be joined and \"softer\" metals such as lead/tin or silver. Manual solding processes use a hand-held iron to heat the components to be joined and the filler metals. Often the filler met- al is in the form of a flux-cored wire with additional flux added to assist with wetting (i.e. flow). Always re- view the Material Safety Data Sheet for the materials involved. Where possible, lead-free solder should be used to avoid potential exposure to lead. For more information on the hazards associated with lead, click Questions: 1. List out the different types of welding 2. What is the best suitable welding for AC MechanicsShri Technologies

44 Shri Technologies Air Conditioning (cooling) System and its unit Air conditioning (often referred to as A/C, AC or aircon) is the process of altering the properties of air (primarily temperature and humidity) to more comfortable conditions, typically with the aim of distrib- uting the conditioned air to an occupied space to improve thermal comfort and indoor air quality. In common use, an air conditioner is a device that lowers the air temperature. The cooling is typically achieved through a refrigeration cycle, but sometimes evaporation or free cooling is used. Air condition- ing systems can also be made based on desiccants. In the most general sense, air conditioning can refer to any form of technology that modifies the condition of air (heating, cooling, (de-)humidification, cleaning, ventilation, or air movement). However, in con- struction, such a complete system of heating, ventilation, and air conditioning is referred to as HVAC (as opposed to AC). Window unit and packaged terminal How a window air conditioner works Air conditioning window unitShri Technologies

45 Parts of a window unit Window unit air conditioners are installed in an open window. The interior air is cooled as a fan blows it over the evaporator. On the exterior the heat drawn from the interior is dissipated into the environment as a second fan blows outside air over the condenser. A large house or building may have several such units, permitting each room to be cooled separately. Packaged terminal air conditioner (PTAC) systems are also known as wall-split air conditioning systems. They are ductless systems. PTACs, which are frequently used in hotels, have two separate units (terminal packages), the evaporative unit on the interior and the condensing unit on the exterior, with an opening passing through the wall and connecting them. This minimizes the interior system footprint and allows each room to be adjusted independently. PTAC systems may be adapted to provide heating in cold weather, ei- ther directly by using an electric strip, gas, or other heater, or by reversing the refrigerant flow to heat the interior and draw heat from the exterior air, converting the air conditioner into a heat pump. While room air conditioning provides maximum flexibility, when used to cool many rooms at a time it is generally more expensive than central air conditioning. The first practical through-the-wall air conditioning unit was invented by engineers at Chrysler Motors and Repair & Maintenance of Window & Split AC offered for sale starting in 1935. Split systems Split-system air conditioners come in two forms: mini-split and central systems. In both types, the inside- environment (evaporative) heat exchanger is separated by some distance from the outside-environment (condensing unit) heat exchanger. Mini-split (ductless) system A mini-split system typically supplies chilled air to a single or a few rooms of a building. Mini-split systems typically produce 9,000 to 36,000 Btu (9,500–38,000 kJ) per hour of cooling.Shri Technologies Advantages of the ductless system include smaller size and flexibility for zoning or heating and cooling in- dividual rooms. The inside wall space required is significantly reduced. Also, the compressor and heat ex- changer can be located farther away from the inside space, rather than merely on the other side of the same unit as in a PTAC or window air conditioner. Flexible exterior hoses lead from the outside unit to the interi- or one(s); these are often enclosed with metal to look like common drainpipes from the roof.