Always Learning. CHAPTER 3 Basics of Heating and Air Conditioning.

Always Learning

CHAPTER 3

Basics of Heating and Air Conditioning

Automotive Heating and Air Conditioning, 6/eBy Thomas S. Birch

Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson EducationUpper Saddle River, NJ 07458 • All rights reserved.3

After studying Chapter 3, the reader will be able to:

1. Explain the purpose of the heating, ventilation, and air-conditioning (HVAC) system in automobiles and other vehicles.

2. Discuss temperature and humidity comfort zones.

3. Explain how heat is measured in both temperature and quantity, using either metric or U.S./British units.

OBJECTIVES



KEY TERMS

• Air distribution • Air management • British thermal unit (Btu) • Cabin filter • Calorie • Celsius • Comfort zone • Fahrenheit • Heat • Humidity • Intensity • Quantity • Relative humidity (RH) • Thermal • Watt



INTRODUCTION

• For the most part, the heating, ventilation, and air-conditioning (HVAC) system of an automobile is designed to provide comfort for the driver and passengers.

• It is intended to maintain in-car temperature and humidity within a range that is comfortable for the people inside and provide fresh, clean air for ventilation.

• This temperature range also helps keep the driver alert and attentive.



INTRODUCTION

• The HVAC system in a vehicle (SEE FIGURE 3–2) can be divided into three closely related subsystems:• Air distribution, also called air management, with

the control system: The HVAC case with doors that control the air flow

• Heating: The heater core heats the air.• Refrigeration, A/C: The evaporator core cools the

air



HEAT

• Heat is a form of basic energy, and, like other forms of energy, heat cannot be created or destroyed. • It can, however, be converted to or from other forms

of energy. SEE FIGURE 3–3 .



HEAT MEASUREMENT

• A heating and air-conditioning technician is concerned with measuring two different aspects of heat: intensity and quantity . • Intensity is what we feel; it is measured in degrees,

on either a Celsius or Fahrenheit scale. • Quantity is the actual amount of heat; it is measured

in either calories or British thermal units (Btu) .



HEAT MEASUREMENT

• HEAT INTENSITY• MEASURING INTENSITY

• HEAT QUANTITY• MEASURING QUANTITY



COMFORT

• Our goal in heating and air conditioning is to maintain a comfortable in-vehicle temperature and humidity.• HUMIDITY• CLEANLINESS



SUMMARY

1. Heat is moved into or out of the passenger compartment to obtain a good comfort level.

2. Heat intensity is measured using the Fahrenheit and Celsius scales, and heat quantity is measured using calories and Btu.

3. The comfort zone of most humans is between 65 and 80°F (21 and 27°C).

4. A/C systems reduce humidity by removing water from the air.

5. HVAC systems clean air because particles are caught by moisture on the evaporator and by filters.



REVIEW QUESTIONS

1. HVAC is short for ______________ , ______________ , and ______________ ______________ .

2. A typical HVAC system uses a(n) ______________ to cool the air, a(n) ______________ to warm the air, and ______________ or ______________ to control the air flow.

3. ______________ is a form of energy that makes us feel warmer, and ______________ is the absence of heat.

4. Heat intensity is commonly measured using either the ______________ or ______________ scale.

5. A temperature of 100°C is equal to ______________ °F.



REVIEW QUESTIONS

6. Heat quantity is commonly measured using units of ______________ or ______________ .

7. Heat always moves from ______________ to ______________ .

8. The A/C system can make air ______________ , ______________ , and ______________ .

9. RH is generally ______________ as air warms up.

10. Moisture that collects on the evaporator reduces the ______________ in the vehicle.



CHAPTER QUIZ

1. A vehicle’s HVAC system contains a(n) ______________ system.

a. A/C

b. heater

c. air distribution

d. All of these



CHAPTER QUIZ

2. Air-conditioning systems control which of the following in a vehicle?

a. Temperature

b. Humidity

c. Air cleanliness

d. All of these



CHAPTER QUIZ

3. Two students are discussing heat movement. Student A says that heat is a form of energy. Student B says heat travels from hot to cold. Who is correct?

a. Student A

b. Student B

c. Both A and B

d. Neither A nor B



CHAPTER QUIZ

4. Heat intensity refers to which of the following?a. The amount of heat in an area

b. The number of Btu in an area

c. The heat individuals feel

d. None of these



CHAPTER QUIZ

5. The freezing point of water is ______________ on the Celsius scale.

a. 100°

b. 0°

c. 32°

d. 212°



CHAPTER QUIZ

6. The boiling point of water is ______________ on the Fahrenheit scale.

a. 0°

b. 32°

c. 100°

d. 212°



CHAPTER QUIZ

7. Student A says that 1 c of heat can increase the temperature of 1 g of water by 1°F. Student B says the temperature will increase 1°C if 1 c is added. Who is correct?

a. Student A

b. Student B

c. Both A and B

d. Neither A nor B



CHAPTER QUIZ

8. The normal temperature for the average human is ______________ .

a. 80°F

b. 100°F

c. 60°F

d. 98.6°F



CHAPTER QUIZ

9. The amount of moisture contained by air is called ______________ .

a. Temperature

b. ambient

c. Humidity

d. None of these



CHAPTER QUIZ

10.In addition to cooling the passenger compartment, an air-conditioning system ______________ .

a. heats the passengers

b. dehumidifies the air

c. puts moisture in the air

d. All of these

Always Learning. CHAPTER 3 Basics of Heating and Air Conditioning.

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