Solutions Manual for
Automotive Technology A
th
Systems Approach 8 Edition
By Jack Erjavec, Rob
Thompson (All Chapters 1-
55, 100% Original Verified,
A+ Grade)
All Chapters Arranged
Reverse: 55-1
This is The Original Solutions
Manual for 8th Edition, All
other Files in The Market are
Fake/Old/Wrong.
, Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 55: Air-
Conditioning Diagnosis and Service
Solution and Answer Guide
ERJAVEC /THOMPSON , AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025,
9780357934616; CHAPTER 55: AIR -CONDITIONING DIAGNOSIS AND SERVICE
TABLE OF CONTENTS
Short Answer................................................................................................................1
Multiple Choice.............................................................................................................3
ASE-Style Review Questions.........................................................................................5
Tech Manual..................................................................................................................9
CONCEPT ACTIVITY 55-1...................................................................................................................9
CONCEPT ACTIVITY 55-2...................................................................................................................9
SHORT ANSWER
1. Explain why special safety precautions must be taken when working with refrigerants.
Answer
Answers will vary but may include: Refrigerant can freeze skin and cause frost bite, do not inhale
refrigerants, do not vent refrigerants into the atmosphere, always work in well ventilated areas, always wear
eye protection.
2. What should you do if you suspect that an alternative refrigerant had been used in the A/C system and it is
not performing properly?
Answer
When you suspect that an alternate refrigerant has been installed in the system, conduct a purity test and
use a refrigerant identifier. Equipment is available to do both of these checks. Knowing what refrigerant is
in the system and what condition it is in will help you determine what steps are needed to properly service
the system.
3. Explain how dye can be used to find leaks in the A/C system.
Answer
Dye is added to the system and then escapes at the location of a leak. The dye is then visible and the cause
of the leak can be determined.
© 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in
whole or in part.
1
, Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 55: Air-
Conditioning Diagnosis and Service
4. What is the purpose of the thermostatic switch in a cycling clutch system?
Answer
In cycling clutch systems, a thermostatic switch is placed in series with the compressor clutch circuit so it
can turn the clutch on or off. It de-energizes the clutch and stops the compressor if the evaporator is at the
freezing point. When the temperature of the evaporator approaches the freezing point, the thermostatic
switch opens the circuit and disengages the compressor clutch. The compressor remains inoperative until
the evaporator temperature rises to the preset temperature, at which time the switch closes and compressor
operation resumes.
5. Why should the probe of an electronic leak detector be placed below the area being checked?
Answer
Refrigerant gas is heavier than air, therefore the probe should be positioned below the test point.
6. What customer complaint may be caused by a plugged evaporator drain?
Answer
Wet floor and a mildew smell
7. What problems can excessive compressor clutch clearance can cause?
Answer
The clutch may slip, causing noise
8. What is the purpose of pulling a vacuum on the A/C system prior to recharging?
Answer
To remove any moisture from the system
9. How will air trapped in the A/C system affect system performance?
Answer
Air can cause the system’s pressures to be incorrect, cause the system to not cool properly, and allow
moisture in the system, which can lead to corrosion. Excessive pressure within the system can restrict the
refrigerant’s ability to change its state from gas to liquid within the refrigeration cycle, which drastically
reduces its heat absorbing and transferring ability. Moisture, on the other hand, can cause freeze-up at the
orifice tube or expansion valve, which restricts refrigerant flow or blocks it completely. Both of these
problems result in intermittent cooling or no cooling at all. Moisture also forms hydrochloric acid when
mixed with refrigerant, causing internal corrosion, which is especially dangerous to the compressor.
MULTIPLE CHOICE
1. Which of the following statements best defines the term “evacuation”?
a. A process in which the refrigerant in a system is released.
b. A condition that exists when a compressor runs until there is no refrigerant left in the system.
c. The process that pulls all traces of air and moisture from the system.
© 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in
whole or in part.
2
, Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 55: Air-
Conditioning Diagnosis and Service
d. A process that uses air to force moisture and dirt out of the system.
Answer: c. Evacuation pulls all traces of air, moisture, and refrigerant from the system.
2. Which of the following statements is true?
a. The suction line must be cool to the touch from the evaporator outlet to the compressor.
b. The liquid line from the condenser outlet to the evaporator inlet should be cool.
c. The evaporator should feel very cold.
d. The accumulator must be cool to the touch.
Answer: b. The refrigerant line from the condenser outlet should be hot, not cool.
3. To charge an air-conditioning system while it is running, the refrigerant should be added to ___.
a. the high side
b. the low side
c. both the high and low sides
d. either the high or the low side
Answer: b. Refrigerant is added to the low side when the compressor is running.
4. All of the following are true statements about flushing an A/C system after a compressor failure, except
___.
a. the condenser must be flushed and the receiver/dryer replaced
b. filter screens are sometimes located in the suction side of the compressor and in the receiver/dryer.
These screens con-fine foreign material to the compressor, condenser, receiver/dryer, and connecting
hoses
c. use only CFCs for flushing. After the system has been flushed, be sure to oil all components that
require it
d. some manufacturers recommend replacing the clogged components and installing a liquid line (inline)
filter just ahead of the expansion valve or orifice tube instead of flushing the system
Answer: c. Compressor failure causes foreign material to pass into the system. The condenser must be
flushed and the receiver/dryer replaced. Filter screens are sometimes located in the suction side of the
compressor and in the receiver/dryer. These screens confine foreign material to the compressor, condenser,
receiver/dryer, and connecting hoses and should be cleaned or replaced Use only recommended flushing
solvents. Never use CFCs or methyl chloroform for flushing. Some recommend instead of flushing the
system, replacing the clogged components and installing an in-line filter just ahead of the expansion valve
or orifice tube.
5. A very important part of a performance test on an A/C system is a pressure test. Pressure also is the key to
the operation of the system. Which of the following statements is not true?
a. Pressure on a substance, such as a liquid, changes its boiling point.
b. The greater the pressure on a liquid, the higher the boiling point.
c. If pressure is placed on a liquid, the liquid freezes at a higher-than-normal temperature.
d. The boiling point can be increased by increasing the pressure on the fluid. It can also be decreased by
reducing the pressure or placing the fluid in a vacuum.
Answer: c. Pressure is what the operation of an A/C unit is all about. It also plays an important part in
engine cooling and the heating system, as well as a ton of other automotive systems. Certain principles
must be known in order to understand and diagnose these systems, some of these facts are: Pressure on a
substance, such as a liquid, changes its boiling point. The greater the pressure on a liquid, the higher the
boiling point. If pressure is placed on a vapor, the vapor condenses at a higher than normal temperature. In
addition, as the pressure on a substance is reduced, the boiling point can also be reduced. For example, the
boiling point of water is 212 °F. The boiling point can be increased by increasing the pressure on the fluid.
© 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in
whole or in part.
3
Automotive Technology A
th
Systems Approach 8 Edition
By Jack Erjavec, Rob
Thompson (All Chapters 1-
55, 100% Original Verified,
A+ Grade)
All Chapters Arranged
Reverse: 55-1
This is The Original Solutions
Manual for 8th Edition, All
other Files in The Market are
Fake/Old/Wrong.
, Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 55: Air-
Conditioning Diagnosis and Service
Solution and Answer Guide
ERJAVEC /THOMPSON , AUTOMOTIVE TECHNOLOGY: A SYSTEMS APPROACH, 8e © 2025,
9780357934616; CHAPTER 55: AIR -CONDITIONING DIAGNOSIS AND SERVICE
TABLE OF CONTENTS
Short Answer................................................................................................................1
Multiple Choice.............................................................................................................3
ASE-Style Review Questions.........................................................................................5
Tech Manual..................................................................................................................9
CONCEPT ACTIVITY 55-1...................................................................................................................9
CONCEPT ACTIVITY 55-2...................................................................................................................9
SHORT ANSWER
1. Explain why special safety precautions must be taken when working with refrigerants.
Answer
Answers will vary but may include: Refrigerant can freeze skin and cause frost bite, do not inhale
refrigerants, do not vent refrigerants into the atmosphere, always work in well ventilated areas, always wear
eye protection.
2. What should you do if you suspect that an alternative refrigerant had been used in the A/C system and it is
not performing properly?
Answer
When you suspect that an alternate refrigerant has been installed in the system, conduct a purity test and
use a refrigerant identifier. Equipment is available to do both of these checks. Knowing what refrigerant is
in the system and what condition it is in will help you determine what steps are needed to properly service
the system.
3. Explain how dye can be used to find leaks in the A/C system.
Answer
Dye is added to the system and then escapes at the location of a leak. The dye is then visible and the cause
of the leak can be determined.
© 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in
whole or in part.
1
, Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 55: Air-
Conditioning Diagnosis and Service
4. What is the purpose of the thermostatic switch in a cycling clutch system?
Answer
In cycling clutch systems, a thermostatic switch is placed in series with the compressor clutch circuit so it
can turn the clutch on or off. It de-energizes the clutch and stops the compressor if the evaporator is at the
freezing point. When the temperature of the evaporator approaches the freezing point, the thermostatic
switch opens the circuit and disengages the compressor clutch. The compressor remains inoperative until
the evaporator temperature rises to the preset temperature, at which time the switch closes and compressor
operation resumes.
5. Why should the probe of an electronic leak detector be placed below the area being checked?
Answer
Refrigerant gas is heavier than air, therefore the probe should be positioned below the test point.
6. What customer complaint may be caused by a plugged evaporator drain?
Answer
Wet floor and a mildew smell
7. What problems can excessive compressor clutch clearance can cause?
Answer
The clutch may slip, causing noise
8. What is the purpose of pulling a vacuum on the A/C system prior to recharging?
Answer
To remove any moisture from the system
9. How will air trapped in the A/C system affect system performance?
Answer
Air can cause the system’s pressures to be incorrect, cause the system to not cool properly, and allow
moisture in the system, which can lead to corrosion. Excessive pressure within the system can restrict the
refrigerant’s ability to change its state from gas to liquid within the refrigeration cycle, which drastically
reduces its heat absorbing and transferring ability. Moisture, on the other hand, can cause freeze-up at the
orifice tube or expansion valve, which restricts refrigerant flow or blocks it completely. Both of these
problems result in intermittent cooling or no cooling at all. Moisture also forms hydrochloric acid when
mixed with refrigerant, causing internal corrosion, which is especially dangerous to the compressor.
MULTIPLE CHOICE
1. Which of the following statements best defines the term “evacuation”?
a. A process in which the refrigerant in a system is released.
b. A condition that exists when a compressor runs until there is no refrigerant left in the system.
c. The process that pulls all traces of air and moisture from the system.
© 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in
whole or in part.
2
, Solution and Answer Guide: Erjavec/Thompson, Automotive Technology: A Systems Approach, 8e © 2025, 9780357934616; Chapter 55: Air-
Conditioning Diagnosis and Service
d. A process that uses air to force moisture and dirt out of the system.
Answer: c. Evacuation pulls all traces of air, moisture, and refrigerant from the system.
2. Which of the following statements is true?
a. The suction line must be cool to the touch from the evaporator outlet to the compressor.
b. The liquid line from the condenser outlet to the evaporator inlet should be cool.
c. The evaporator should feel very cold.
d. The accumulator must be cool to the touch.
Answer: b. The refrigerant line from the condenser outlet should be hot, not cool.
3. To charge an air-conditioning system while it is running, the refrigerant should be added to ___.
a. the high side
b. the low side
c. both the high and low sides
d. either the high or the low side
Answer: b. Refrigerant is added to the low side when the compressor is running.
4. All of the following are true statements about flushing an A/C system after a compressor failure, except
___.
a. the condenser must be flushed and the receiver/dryer replaced
b. filter screens are sometimes located in the suction side of the compressor and in the receiver/dryer.
These screens con-fine foreign material to the compressor, condenser, receiver/dryer, and connecting
hoses
c. use only CFCs for flushing. After the system has been flushed, be sure to oil all components that
require it
d. some manufacturers recommend replacing the clogged components and installing a liquid line (inline)
filter just ahead of the expansion valve or orifice tube instead of flushing the system
Answer: c. Compressor failure causes foreign material to pass into the system. The condenser must be
flushed and the receiver/dryer replaced. Filter screens are sometimes located in the suction side of the
compressor and in the receiver/dryer. These screens confine foreign material to the compressor, condenser,
receiver/dryer, and connecting hoses and should be cleaned or replaced Use only recommended flushing
solvents. Never use CFCs or methyl chloroform for flushing. Some recommend instead of flushing the
system, replacing the clogged components and installing an in-line filter just ahead of the expansion valve
or orifice tube.
5. A very important part of a performance test on an A/C system is a pressure test. Pressure also is the key to
the operation of the system. Which of the following statements is not true?
a. Pressure on a substance, such as a liquid, changes its boiling point.
b. The greater the pressure on a liquid, the higher the boiling point.
c. If pressure is placed on a liquid, the liquid freezes at a higher-than-normal temperature.
d. The boiling point can be increased by increasing the pressure on the fluid. It can also be decreased by
reducing the pressure or placing the fluid in a vacuum.
Answer: c. Pressure is what the operation of an A/C unit is all about. It also plays an important part in
engine cooling and the heating system, as well as a ton of other automotive systems. Certain principles
must be known in order to understand and diagnose these systems, some of these facts are: Pressure on a
substance, such as a liquid, changes its boiling point. The greater the pressure on a liquid, the higher the
boiling point. If pressure is placed on a vapor, the vapor condenses at a higher than normal temperature. In
addition, as the pressure on a substance is reduced, the boiling point can also be reduced. For example, the
boiling point of water is 212 °F. The boiling point can be increased by increasing the pressure on the fluid.
© 2025 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in
whole or in part.
3
