1. Automotive Heating and Air Conditioning, Fifth Edition By Tom Birch © 2010 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 FIGURE 3-1 The air moves through the HVAC system’s ducts, evaporator, and cabin/clean air filter (a). Excess heat, moisture, dust, and pollen are removed to condition the air and make it more comfortable (b).(a is provided courtesy of Toyota Motor Sales USA, Inc.)

2. Automotive Heating and Air Conditioning, Fifth Edition By Tom Birch © 2010 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 FIGURE 3-2 A typical HVAC system has a choice of two inlets (right), a blower to move the air, an A/C evaporator core and heater core, and several air discharge outlets.

3. Automotive Heating and Air Conditioning, Fifth Edition By Tom Birch © 2010 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 FIGURE 3-3 Heat, like light and electricity, is one of the basic forms of energy. (Courtesy of Chrysler LLC)

4. Automotive Heating and Air Conditioning, Fifth Edition By Tom Birch © 2010 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 FIGURE 3-4 An engine converts potential energy from fuel into mechanical energy.

5. Automotive Heating and Air Conditioning, Fifth Edition By Tom Birch © 2010 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 FIGURE 3-5 About one-third of the heat in an engine is converted into useful power. The other two-thirds is lost to the cooling and exhaust systems.

6. Automotive Heating and Air Conditioning, Fifth Edition By Tom Birch © 2010 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 FIGURE 3-6 One of the basic principles of heat is that it always travels toward a colder area, and the rate of movement is determined by the temperature difference.

7. Automotive Heating and Air Conditioning, Fifth Edition By Tom Birch © 2010 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 FIGURE 3-7 (a) In a cooling system, heat flows from the hot engine parts to the colder coolant (b),then to the colder radiator, and then to the colder ambient air (c).

8. Automotive Heating and Air Conditioning, Fifth Edition By Tom Birch © 2010 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 FIGURE 3-8 Heat intensity is measured using a thermometer. The two common measuring scales, Celsius and Fahrenheit, are shown here. This thermometer is also marked with important temperatures.

9. Automotive Heating and Air Conditioning, Fifth Edition By Tom Birch © 2010 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 FIGURE 3-9 Water is a solid, ice, below 32°F, and adding heat will change it to a liquid. Adding more heat will cause water to boil (above 212°F) and turn to vapor called steam.

10. Automotive Heating and Air Conditioning, Fifth Edition By Tom Birch © 2010 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 FIGURE 3-10 A combined scale can be used to convert temperatures between the Celsius and Fahrenheit scales.

11. Automotive Heating and Air Conditioning, Fifth Edition By Tom Birch © 2010 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 FIGURE 3-11 We put about 115,000 Btu of heat energy in the car with each gallon of gas we buy.

12. Automotive Heating and Air Conditioning, Fifth Edition By Tom Birch © 2010 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 FIGURE 3-12 A wooden match produces about 1 Btu of heat when it burns. This amount of heat will increase the temperature of 1 lb of water 1°F. (Courtesy of Fluke; reproduced with permission)

13. Automotive Heating and Air Conditioning, Fifth Edition By Tom Birch © 2010 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 FIGURE 3-13 Human comfort is greatly affected by temperature and humidity. (Courtesy of www.ergonomics4schools.com)

14. Automotive Heating and Air Conditioning, Fifth Edition By Tom Birch © 2010 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 FIGURE 3-14 When air comes into contact with the cold evaporator, excess moisture forms dew. This condensed moisture leaves the car through the evaporator drain.

15. Automotive Heating and Air Conditioning, Fifth Edition By Tom Birch © 2010 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 FIGURE 3-15 The dew on the evaporator traps dust and pollen that comes in contact with it; the dust and pollen drain out with the water.