Deck 55: Heating and Air Conditioning Diagnosis and Service

Question 1

R-12 is stored in light blue containers.

Answer 1

False

Question 2

It is acceptable to mix refrigerants in a vehicle's A/C system.

Answer 2

False

Question 3

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

Answer 3

True

Question 4

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

Question 5

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

Question 6

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

Question 7

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 8

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

Question 9

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

Question 10

EPA certification is required to purchase R-12.

Question 11

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

Question 12

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

Question 13

R-134a is stored in yellow containers.

Question 14

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

Question 15

EPA certification is required to service R-12 A/C systems.

Question 16

Refrigerant is lighter than oxygen.

Question 17

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

Question 18

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

Question 19

Toyota recommends the use of leak-detecting dyes.

Question 20

There is a specific recovery/recycle/recharge machine designed to service R-1234yf systems.

Question 21

When is a manifold gauge set used on an A/C system ?

A)discharging
B)charging
C)evacuating
D)All the answers are correct.

Question 22

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 23

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 the answers are correct.

Question 24

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 25

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 26

Which statement about orifice tube systems is false?

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 27

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 28

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 29

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

Question 30

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 31

Separate service equipment must be used for different refrigerants.

Question 32

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

Question 33

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 34

Which of the following steps is recommended when 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 it with the R134a type and the same amount.

Question 35

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 36

Which does not 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 37

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

Question 38

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 39

Which statement 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 40

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 41

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 42

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 the answers is correct.

Question 43

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 44

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 45

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 46

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 47

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 48

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 49

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 50

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 51

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 52

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 the answers are correct.

Question 53

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

A)ASE
B)MACS
C)ACME
D)both A and B

Question 54

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 55

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 the answers are correct.

Question 56

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 57

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 58

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 59

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

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

Question 60

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

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

Question 61

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 62

Before recovering refrigerant, the refrigerant must be _____.

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

Question 63

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 64

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

Question 65

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 66

During a performance test, both the low-side and high-side pressures are above normal. Technician A says the system is overcharged. T echnician B says there is insufficient airflow through the condenser. Who is correct?

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

Question 67

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

Question 68

When evacuating an A/C system, the vacuum pump should remain on and connected to the system for at least 30 minutes after reaching _____ inches of mercury (in. Hg).

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

Question 69

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 70

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

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

Question 71

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 72

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 the answers are correct.

Question 73

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

Question 74

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

Question 75

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 76

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 77

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 the answers are correct.

Question 78

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 79

During a performance test, both the low-side and high-side pressures are below normal. What would cause this problem?

A)The system is undercharged.
B)There's a defective (open)high-pressure cutout switch.
C)There's a restriction in the liquid line.
D)The condenser has insufficient airflow.

Question 80

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