Deck 55: Air-Conditioning Diagnosis and Service

Question 1

A manifold gauge set can be used during the evacuation of the A/C system.

Answer 1

True

Question 2

A single drop of water in an A/C refrigeration system may cause damage to the system.

Answer 2

True

Question 3

Refrigerant is lighter than oxygen.

Answer 3

False

Question 4

R-12 is stored in light blue containers.

Question 5

A manifold gauge set can be used during A/C system diagnosis.

Question 6

The high- and low-pressure fittings must be changed during an R-12 to R-134a conversion.

Question 7

A problem with the HVAC mode control linkage, doors, or motor circuit cannot set a DTC.

Question 8

R-134a is stored in yellow containers.

Question 9

Some cabin air filter elements are impregnated with baking soda and a filter with a biocidal cartridge. Both prevent the growth of bacteria, mold, mildew, algae, and yeast.

Question 10

According to Section 609 of the Federal Clean Air Act, no one repairing or servicing a motor
vehicle's A/C system can do so unless that person is properly trained and certified.

Question 11

The high-voltage electrical system of a hybrid vehicle should be shut down and isolated from the vehicle prior to working on the A/C compressor.

Question 12

All new vehicles sold in the United States must have a cabin air filter or a slot where one can be installed.

Question 13

In some states and provinces, you must be certified by an EPA-approved program to buy refrigerant.

Question 14

All R-12 test hoses have a Schrader core depressor in them.

Question 15

In an R-134a system, pressure and performance testing are the only ways to identify low refrigerant levels.

Question 16

Temperature/pressure charts are not required when manifold gauges are used in A/C performance testing.

Question 17

A manifold gauge set is used to determine both high-side and low-side pressures in the refrigeration system.

Question 18

Warm underhood temperatures produce lower than normal A/C system pressures.

Question 19

A sight glass is normally found on systems using R-134a and an orifice tube.

Question 20

In an R-12 to R-134a conversion, a high-pressure cutoff switch should be installed if the system does not have one.

Question 21

R-12 and R-134a _____.

A) should never be mixed
B) may be mixed after a system has been converted from R-12 to R-134a
C) use the same manifold gauge sets
D) all answers are correct

Question 22

EPA certification is required to _____.

A) service R-12 A/C systems
B) purchase R-12
C) both "service R-12 A/C systems" and "purchase R-12"
D) neither "service R-12 A/C systems" nor "purchase R-12"

Question 23

Technician A says evacuating (pumping down) an air-conditioning system removes air and moisture from the system. Technician B says evacuating (pumping down) an air-conditioning system must be done anytime the system has been opened for repairs. Who is correct?

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

Question 24

When is a manifold gauge set used?

A) discharging
B) charging
C) evacuating
D) all answers are correct

Question 25

An R-12 to R-134a conversion procedure is being discussed. Technician A says leak-test the system and conduct a performance test prior to removing the R-12. Technician B says leak-test the system and conduct a performance test after charging the system with R-134a. Who is correct?

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

Question 26

Which of the following cannot cause excessive heat?

A) a loose or damaged control cable
B) a heater control valve stuck open
C) a water flow control valve not opening fully
D) a faulty thermostatic fan

Question 27

Technician A says the presence of oil around a fitting of an air-conditioning line may indicate an oil leak but not a refrigerant leak. Technician B says using an electronic leak detector is the best way to find the source of a refrigerant leak. Who is correct?

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

Question 28

The filling level of a refrigerant container should never exceed _____ percent of the container's gross weight rating.

A) 50
B) 60
C) 75
D) 90

Question 29

Technician A says pinhole leaks in the evaporator may be caused by acid formed when water and refrigerant are mixed. Technician B says leaks are most often found at hose connections and at the various fittings and joints in the system. Who is correct?

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

Question 30

Which of the following statements is NOT true about orifice tube systems?

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 orifice tube should be cool
C) The evaporator inlet should feel very cold
D) The accumulator must be cool to the touch

Question 31

When replacing a typical A/C system component, the system must be discharged _____.

A) approximately 2 percent
B) approximately 50 percent
C) approximately 75 percent
D) completely

Question 32

Technician A says the refrigerant oil container should not be opened until it is time to use it and should be capped immediately after use. Technician B says after the system has been opened, compressed air should be used to flush dirt, moisture, and old refrigerant oil out of the system. Who is correct?

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

Question 33

Which of the following statements best defines the term "evacuation"?

A) Evacuation is a process in which the refrigerant in a system is released
B) Evacuation is a condition that exists when a compressor runs until there is no refrigerant left in the system
C) Evacuation is a process that removes all traces of air, moisture, and refrigerant from the system
D) Evacuation is a process that uses air to force moisture and dirt out of the system

Question 34

Technician A says air in the system can cause excessive pressure within the A/C system. Technician B says moisture can cause freeze-up at the expansion valve. 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 is recommended while converting an R-12 system to R-134a?

A) Permanently install conversion fittings using new hose clamps around fittings
B) Install conversion labels and remove the R-12 label
C) Recharge the system with R-134a to approximately 80 percent of the original R-12 charge
D) Remove all oil in the system and replace with the R134a type and the same amount

Question 36

Technician A says if the suction line to the compressor is covered with thick frost, this might indicate that the expansion valve is flooding the evaporator. Technician B says the formation of frost on the outside of a line or component means there is a restriction to the flow of refrigerant. Who is correct?

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

Question 37

A/C parts replacement is being discussed. Technician A says if the system has been open for more than two minutes, the entire system must be completely evacuated and a new accumulator must be installed. Technician B says if the compressor has internal damage the condenser may need to be flushed and the receiver/dryer or accumulator replaced. Who is correct?

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

Question 38

Technician A says there should be a gradual change from hot to warm as you move your hand along the return bends of the condenser from the bottom to the top. Technician B says a restriction in the condenser will be evident by a sudden change in temperature. Who is correct?

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

Question 39

Technician A says the oil level of the compressor should be checked every year. Technician B says the system should be charged only after it has been completely evacuated. Who is correct?

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

Question 40

A technician is trying, without success, to connect a 30-pound container of R-12 to his R-134a manifold gauge set. Technician A says the R-12 fitting is female and the gauge set fitting is also female. Technician B says the R-134a manifold gauge set uses a half-inch Acme thread, whereas the R-12 tank fitting has a standard thread. Who is correct?

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

Question 41

R-12 to R-134a conversions are being discussed. Technician A says the original receiver/dryer or accumulator should not be replaced. Technician B says permanently install conversion fittings using a thread-locking chemical. Who is correct?

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

Question 42

Technician A says the cabin air filter should be replaced every 12,000 to 15,000 miles (19,300 to 24,140 km) or once a year. Technician B says some cabin air filters have a charcoal layer for odor absorption. Who is correct?

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

Question 43

During a performance test, both the low-side and high-side pressures are below normal. Which of the following could cause this problem.

A) System is undercharged
B) Defective [open] high-pressure cutout switch
C) Restriction in liquid line
D) Insufficient airflow through the condenser

Question 44

Unpleasant odors coming from the A/C system can be eliminated by ______.

A) backflushing the A/C system with alcohol
B) evacuating and recharging the system
C) cleaning the evaporator core with a disinfectant solution
D) draining and replacing the refrigerant oil

Question 45

The EPA-approved certification exam on refrigerant recovery and recycling is administered by _____.

A) ASE
B) MACS
C) both "ASE" and "MACS'
D) neither "ASE" nor "MACS'

Question 46

Frost on the outside of the receiver/dryer, but not on the liquid line between the condenser and receiver/dryer indicates ______.

A) the system is overcharged
B) a clogged accumulator
C) a restriction in the suction line
D) a restriction in the receiver/dryer

Question 47

The owner of a car complains of a whistle or hiss only after the engine is shut down and only when the air-conditioning has been running. Technician A says there is a broken or leaking vacuum hose inside the dash. Technician B says this is a normal noise caused by the pressure of the refrigerant equalizing after the engine is turned off. Who is correct?

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

Question 48

Large amounts of black dust around the clutch plate is an indication of _____.

A) leaking compressor seal
B) defective compressor clutch bearing
C) slipping A/C belt
D) restriction in high side

Question 49

Technician A always wears safety glasses when working on air-conditioning systems. Technician B makes sure there are no open flames in the area prior to working on the A/C system. Who is correct?

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

Question 50

A loud squealing noise could be caused by ______.

A) a worn compressor clutch
B) oil on the compressor clutch
C) a seized compressor
D) all answers are correct

Question 51

A vehicle is being diagnosed for poor A/C performance. The engine is started, and when the system is set to MAX A/C, the compressor engages normally. When the temperature control knob is moved from hot to cool, only hot air blows out of the A/C outlets. Technician A says there is a problem with the air duct system or the controls. Technician B says the system is low on refrigerant. Who is correct?

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

Question 52

Technician A uses the ohmmeter function of a DMM [digital multimeter] to test the resistor block for opens. Technician B tests the resistor block with a lab scope. Who is correct?

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

Question 53

Technician A says the sight glass is located in the suction line, between the accumulator and compressor. Technician B says the sight glass is located on the receiver/dryer. Who is correct?

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

Question 54

Bubbles in the sight glass of an R12 system indicate _____.

A) air in the system
B) the system is low on refrigerant
C) evaporator flooding
D) none of these answers is correct

Question 55

During a performance test, both the low-side and high-side pressures are above normal. Which of the following could cause this problem?

A) The system is overcharged
B) Insufficient airflow through the condenser
C) Both "The system is overcharged" and "Insufficient airflow through the condenser"
D) Neither "The system is overcharged" nor "Insufficient airflow through the condenser"

Question 56

The A/C compressors on hybrid vehicles have _____colored wires and wire harness covers to indicate they carry high voltage.

A) red
B) yellow
C) orange
D) violet

Question 57

Technician A says the suction line connected to the compressor should be cool to the touch. Technician B says the discharge line from the compressor to the condenser should be hot along its entire length. Who is correct?

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

Question 58

The leak-test dye in an A/C system will appear luminous yellow-green when illuminated by a(n) _____ light.

A) infrared [IR]
B) ultraviolet [UV]
C) blue laser
D) 5,200°K mercury vapor

Question 59

How are manifold gauge service hoses colored?

A) low = green, center = orange, high = red
B) low = green, center = yellow, high = red
C) low = blue, center = yellow, high = red
D) low = blue, center = green, high = red

Question 60

The manifold gauge set has an inches-of-mercury [vacuum] scale on the _____ gauge.

A) low-side
B) high-side
C) auxiliary gauge
D) all answers are correct

Question 61

Technician A stores recycled refrigerant in emptied new refrigerant tanks. Technician B stores recycled refrigerant in UL-approved containers. Who is correct?

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

Question 62

Normally the A/C system is charged _____ with the engine running.

A) on the low side as a vapor
B) on the low side as a liquid
C) on the high side as a vapor
D) on the high side as a liquid

Question 63

Technician A says refrigerant hoses can be repaired. Technician B says damaged refrigerant hoses cannot be repaired and must be replaced. Who is correct?

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

Question 64

R-12 systems use ____________________based oils.

Question 65

The blower motor on a vehicle does not run when the fan switch is in the low and medium position. It works properly when it is in the high position. Technician A says the problem is in the resistor block. Technician B says the problem is in the blower motor. Who is correct?

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

Question 66

Upon reaching a 26 to 29 in. Hg vacuum reading, the vacuum pump should remain on and connected to the system for at least ____________________ minutes while evacuating an A/C system.

Question 67

Refrigerant exposed to an open flame will produce a(n) ____________________ gas.

Question 68

Before recovering refrigerant, the refrigerant must be _____.

A) heated
B) measured
C) filtered
D) identified

Question 69

____________________ testing provides a measure of an air-conditioning system's operating efficiency.

Question 70

When evacuating an A/C system, the vacuum pump should remain on and connected to the system for at least thirty minutes after _____ inches of mercury (in. Hg) is reached.

A) 12 to 15
B) 18 to 21
C) 22 to 25
D) 26 to 29

Question 71

A complaint concerning water on the front floor carpeting even in dry weather could be caused by _____

A) evaporator flooding
B) a saturated desiccant bag
C) a clogged evaporator case drain
D) all answers are correct

Question 72

Technician A says all the refrigerant oil in the A/C system is contained inside the compressor. Technician B says the oil circulates throughout the entire A/C system and at any given moment each component holds a small amount of oil. Who is correct?

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

Question 73

The ____________________ is a test instrument used to check the coil of a compressor clutch.

Question 74

Electronic leak detectors are being discussed. Technician A checks for leaks with the engine off, the shop doors closed, and the overhead fans turned off. Technician B checks for leaks outdoors with the engine running. Who is correct?

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

Question 75

The compressor on a vehicle has seized. Besides the new compressor, what other component should also be replaced?

A) the receiver/dryer
B) the evaporator
C) the condenser
D) all answers are correct

Question 76

A compressor clutch that chatters when the A/C is off could be caused by _____.

A) defective compressor bearings
B) insufficient clearance between the rotor pulley and the armature plate
C) low refrigerant oil level
D) excessive drive belt tension

Question 77

R-134a systems use synthetic ____________________ oils.

Question 78

When installing an A/C system filter: if the filter does not have an orifice tube, it should be installed in the _____ line.

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

Question 79

If refrigerant comes into contact with your eyes or skin, it may cause ____________________.

Question 80

When an orifice tube A/C system has remained open for any length of time, the ____________________ should be replaced.