Deck 54: Heating and Air Conditioning

Question 1

High relative humidity is more comfortable than low humidity.

Answer 1

False

Question 2

R-134a is a hydrofluorocarbon.

Answer 2

True

Question 3

A liquid will boil at a lower temperature when it is put under pressure.

Answer 3

False

Question 4

The heater core may be plugged if the inlet hose feels hot and the outlet hose feels cool.

Question 5

PAG oil works well with R-12 refrigerant.

Question 6

Section 609 of the U.S. Clean Air Act of 1990 requires that all service technicians who work on A/C systems must be certified in proper refrigerant recovery and recycling.

Question 7

Aluminum tubing is often used to connect air-conditioning components where flexibility is not required.

Question 8

Heat always flows from a warmer object to a colder one.

Question 9

Federal safety standards do not require that all motor vehicles be equipped with passenger compartment heating and windshield defrosting systems.

Question 10

The heater control valve is often called the water flow valve.

Question 11

All manufacturers recommend reverse flushing their heater cores.

Question 12

In most vehicles, the air-conditioning compressor will turn off when the defroster is selected by the driver and the ambient temperature is more than 35°F.

Question 13

A malfunctioning engine thermostat can be the cause of poor heater performance.

Question 14

An A/C system cools the air by moving heat from the confined space of the passenger compartment to the engine cooling system.

Question 15

More than half of the heat that is in a vehicle's passenger compartment comes from solar radiation.

Question 16

Most current HVAC systems use electric servomotors to move the various doors.

Question 17

Refrigerant is a low-pressure liquid as it leaves the condenser.

Question 18

Most vehicles have a cabin filtration system that cleans the air before it enters the passenger compartment.

Question 19

Air-conditioning systems that use an accumulator come equipped with a sight glass.

Question 20

A thermostatic expansion valve is mounted on the outlet side of the evaporator.

Question 21

Technician A says suction lines connect the accumulator to the compressor. Technician B says discharge lines connect the compressor to the condenser. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 22

Technician A says the normal operating pressures of R-134a are slightly lower than the pressures of R-12. Technician B says R-134a boils at 134 degrees Fahrenheit. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 23

Technician A says R-12 air-conditioning technicians must be certified. Technician B says R-12 air-conditioning equipment must be certified. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 24

Heater control valves are operated by a ______.

A) cable
B) thermostat
C) vacuum motor
D) all answers are correct

Question 25

On which of the following laws of nature is the air-conditioning system based?

A) heat flow
B) heat absorption
C) pressure and boiling points
D) all answers are correct

Question 26

Technician A says refrigerant leaves the compressor as a high-pressure liquid. Technician B says the condenser changes the high-pressure liquid refrigerant into a high-pressure vapor. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 27

A heating system includes all the following parts EXCEPT:

A) heater core
B) ventilation system
C) receiver/dryer
D) distribution plenum

Question 28

Which of the following oils can be used in an R-134a system?

A) mineral oil
B) matural oil
C) castor oil
D) PAG oil

Question 29

Which of the following statements is not correct?

A) The condenser is normally mounted in front of the radiator
B) The receiver/dryer is a storage tank for liquid refrigerant from the condenser
C) The accumulator is located between the condenser and the receiver/dryer
D) All answers are correct

Question 30

Which of the following may be electrically connected in series with the compressor electromagnetic clutch?

A) ambient temperature switch
B) thermostatic switch
C) pressure cycling switch
D) all answers are correct

Question 31

A poor heat condition is being discussed. Technician A says a disconnected engine vacuum hose could not cause the problem. Technician B says a seized blend door could cause the problem. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 32

Which of the following statements concerning R-12 is correct?

A) R-12 is a hydrofluorocarbon.
B) R-12 boils at 0 degrees Fahrenheit (-18 Celsius)
C) R-12 is destructive to Earth's ozone layer
D) All answers are correct

Question 33

Technician A says when the pressure applied to a liquid is increased, the boiling point decreases. Technician B says when the pressure on a liquid is suddenly released, heat energy is absorbed into the liquid. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 34

Technician A says R-12 is a chlorofluorocarbon (CFC) that damages Earth's ozone layer. Technician B says R-134a is a hydrofluorocarbon (HFC) that causes even greater damage. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 35

Which of the following statements concerning evaporators is NOT true?

A) Low-pressure liquid enters the evaporator at the bottom
B) High-pressure vapor leaves the evaporator at the top
C) The evaporator is located underneath the dash
D) Air passing over the evaporator loses its heat to the cooler surface of the core

Question 36

Which of the following statements is NOT correct?

A) The evaporator changes heated refrigerant to a liquid
B) Automatic temperature controls maintain a set passenger compartment temperature
C) Air-conditioning/heater systems can be computer controlled
D) Heaters and air conditioners use the same plenum chambers

Question 37

A poor heat out of the floor duct condition is being discussed. Technician A says the coolant level in the engine's cooling system may be low. Technician B says the engine's thermostat may be faulty. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 38

All materials or substances, as cold as ______, have heat in them.

A) -100°F (-73°C)
B) -134°F (-92°C)
C) -212°F (-136°C)
D) -459°F (-273°C)

Question 39

Technician A says the thermostatic expansion valve and the fixed orifice tube perform the same function. Technician B says heat from the evaporator core surface is lost to the boiling and vaporizing refrigerant. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 40

Which of the following statements is correct?

A) Refrigerant leaves the compressor as a high-pressure, high-temperature liquid
B) Refrigerant leaves the condenser as a low-pressure, high-temperature liquid
C) Refrigerant returns to the compressor as a low-pressure, high-temperature vapor
D) None of these answers is correct

Question 41

The blower motor does not run in any fan switch position. A check with a DMM reveals that power is getting to the motor. Technician A says the motor ground is bad. Technician B says the motor is burned out. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 42

Airflow control valves in the ventilation duct work are operated by ______.

A) electric motors
B) vacuum motors
C) cables
D) all answers are correct

Question 43

Technician A says an A/C system using CO₂ [carbon dioxide] for a refrigerant will not contribute to global warming and is environmentally friendly. Technician B says CO₂ refrigerant does not need to be recovered and recycled. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 44

The boiling point of a liquid increases as ______.

A) the pressure applied to it decreases
B) the pressure applied to it increases
C) exposed surface area of liquid decreases
D) exposed surface area of liquid increases

Question 45

Technician A repairs a leaking heater core. Technician B replaces it with a new core. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 46

Technician A says hybrid vehicles have an electric water pump to circulate coolant through the heater core when the engine is stopped. Technician B says hybrid vehicles have a hot coolant storage tank to provide heat for the passenger compartment when the engine is shut down. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 47

Heater cores with electric PTC heater strips are used on what type of vehicle?

A) pickup trucks and SUVs
B) economy cars
C) hybrid vehicles
D) luxury cars

Question 48

A vehicle with insufficient heater performance is being discussed. Technician A says the problem could be a stuck-open engine thermostat. Technician B says air could be trapped inside the heater core. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 49

A subcooler is located ______.

A) inside the receiver/drier
B) between the evaporator and accumulator
C) at the bottom of the condenser
D) aft of the torpedo room

Question 50

Technician A says the compressor can pump both liquids and vapor. Technician B says the compressor is driven off the crankshaft by a belt. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 51

Variable displacement compressors are normally _____ compressors with a pivoting wobble plate.

A) radial
B) inline
C) scroll
D) axial

Question 52

The refrigerant is at its lowest pressure and temperature at the ______.

A) compressor suction port [inlet]
B) evaporator orifice [inlet]
C) condenser outlet
D) receiver/drier inlet

Question 53

Before 1994, most manufacturers used _____ as a refrigerant.

A) R-12
B) R-22
C) R-134a
D) R-152a

Question 54

Which of these statements is true?

A) Water vaporizes into steam at 212°F
B) Steam condenses into water at 212°F
C) both "Water vaporizes into steam at 212°F" and "Steam condenses into water at 212°F"
D) neither both "Water vaporizes into steam at 212°F" nor "Steam condenses into water at 212°F"

Question 55

Technician A says European and Japanese manufacturers shipping vehicles to the US will eliminate R-134a A/C systems by 2017. Technician B says the United States will switch to R-22 in 2015. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 56

Technician A says hybrid vehicles use electrically driven high voltage A/C compressors. Technician B says the compressors for hybrids use the same refrigerant oil as regular vehicles. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 57

Technician A says a hybrid vehicle has a large reservoir of liquid refrigerant to keep the passenger compartment cool during long periods when the engine is shut down. Technician B says some hybrid vehicles have electrically driven A/C compressors. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 58

Technician A says in most cases, problems with the heating system are problems with the engine's cooling system. Technician B says a restricted heater return hose can cause excess heat in the passenger compartment. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 59

If little or no resistance is felt while operating the temperature control lever, the problem is most likely which of the following?

A) There is a vacuum leak between the intake manifold and control valve
B) The control cables have slipped loose from the dash control or door arm
C) The electric servomotor is burnt out
D) The heat control valve is seized

Question 60

Technician A says the magnetic clutch is usually pressure controlled, cycling the compressor on and off to regulate system temperature or pressure. Technician B says the clutch operates continually when the system is turned on. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 61

Thermal expansion valves are being discussed. Technician A says the TEV regulates the refrigerant flow to the evaporator by balancing the inlet flow to the outlet temperature. Technician B says the TEV is closed when the temperature at the outlet of the evaporator is high. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 62

____________________ valves are used to seal the compressor inlet and outlet ports.

Question 63

The evaporator is located _____.

A) in front of the radiator
B) between the right front inner fender and the firewall
C) below the condenser
D) under the dash

Question 64

The change from a liquid to a vapor is called ____________________.

Question 65

A sight glass is normally found on systems using R-12 and a(n) _____.

A) orifice tube
B) subcooler
C) accumulator
D) thermal expansion valve

Question 66

Which of the following components is NOT part of a receiver/drier?

A) pressure relief valve
B) expansion valve
C) desiccant bag
D) sight glass

Question 67

When the air-conditioning is set to the maximum position, passenger compartment air is ____________________.

Question 68

The heater ____________________ is generally designed and constructed much like a miniature radiator.

Question 69

Technician A says a CCOT system has an expansion valve and a sight glass. Technician B says a CCOT system has an accumulator. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 70

____________________ heat is the amount of heat necessary to change the state of a substance.

Question 71

Technician A says the receiver/drier is located on the low [pressure] side of the A/C system. Technician B says the accumulator is located on the low side of the system. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 72

The purpose of the desiccant bag in a receiver/drier or accumulator is to ______.

A) ensure that only liquid refrigerant enters the expansion orifice
B) ensure that only vapor enters the compressor
C) absorb moisture inside the system
D) all answers are correct

Question 73

The ____________________ displacement compressor automatically changes volume and the amount of refrigerant flow.

Question 74

The blower motor fan is sometimes referred to as a(n) ____________________ cage.

Question 75

The supply of outside air that flows through the ventilation system inlet grille when the car is moving is called ____________________ air.

Question 76

The ozone layer protects Earth from receiving an excessive amount of the sun's ____________________ rays.

Question 77

The dash-mounted switch and the blower motor ____________________ block are used to control the blower motor speed.

Question 78

The largest and coolest line/hose in the A/C system is the ______ line.

A) liquid
B) discharge
C) suction
D) equalizer

Question 79

The high pressure cutout switch disengages the compressor clutch when high-side pressure reaches _____ psi.

A) 250 to 300
B) 300 to 350
C) 350 to 400
D) 450 to 500

Question 80

The change from a vapor to a liquid is called ____________________.