Deck 21: Mechanical Troubleshooting

Question 1

Which of the following could be the reason that the subcooling would be low on an air conditioning system?

A) dirty or blocked condenser coil
B) system operating in low ambient conditions
C) liquid line restriction
D) noncondensable gas in the system

Answer 1

A

Question 2

Which of the following would be considered noncondensable gas/es in a refrigeration system?

A) nitrogen
B) refrigerant
C) vaporized refrigerant oil
D) air
E) both a and d

Answer 2

E

Question 3

If, while troubleshooting an R-410A residential air conditioning system at near design conditions, the operating pressures are found to be 118 psig on the low side and 440 psig on the high side, it is most likely that the system is

A) operating with a dirty air filter
B) operating with a refrigerant overcharge
C) operating with an undercharge of refrigerant
D) operating properly

Answer 3

D

Question 4

Which of the following is NOT a condition of the belt being too tight on a blower?

A) bearing damage
B) belt slippage
C) excessive noise
D) excessive belt breakage

Question 5

Which is NOT a cause for low superheat in an air conditioning system?

A) refrigerant undercharge
B) overfeeding metering device
C) dirty air filters
D) restricted airflow through the evaporator coil

Question 6

Which type of bearings do most residential fan motors use?

A) ball
B) reed
C) sleeve
D) nylon

Question 7

Which of the following is a condition of an air conditioning system that is overcharged?

A) increased evaporator superheat
B) reduced evaporator efficiency
C) low operating pressures
D) evaporator coil frosting

Question 8

To use the electronic leak detector, the system must contain at least some refrigerant. If the system is operating with a small leak, plenty of pressurized refrigerant is left in the system. But if the system is void of refrigerant, it must first be pressurized with __________, to which a trace of refrigerant has been added.

A) halogen
B) hydrogen
C) nitrogen
D) oxygen

Question 9

If, while troubleshooting a residential central air conditioning system, the technician notices frost on the suction line, what is the most likely problem?

A) dirty air filter
B) defective condenser fan motor
C) dirty condenser
D) high superheat
E) normal operation

Question 10

Which type of leak detection uses a refrigerant additive charged into the refrigeration system?

A) halide
B) soap bubbles
C) electronic
D) UV leak detection

Question 11

Which type of leak detection involves burning refrigerant?

A) halide
B) electronic
C) soap bubbles
D) ultraviolet light

Question 12

If, while troubleshooting an R-22 residential air conditioning system at near design conditions, the operating pressures are found to be 40 psig on the low side and 116 psig on the high side, it is most likely that the system is

A) overcharged
B) operating with a dirty condenser
C) undercharged
D) operating properly

Question 13

Where is the high-side access port located on most residential central air conditioning systems?

A) discharge line
B) liquid line
C) suction line
D) directly on the compressor high side

Question 14

Which is NOT a cause of high superheat in an air conditioning system?

A) refrigerant undercharge
B) overfeeding metering device
C) underfeeding metering device
D) excessive airflow through the evaporator coil

Question 15

Which of the following could be the cause for excessive subcooling in an air conditioning system?

A) dirty or blocked condenser coil
B) defective condenser fan motor
C) system operating in low ambient conditions
D) service panels removed from condensing unit

Question 16

Most modern residential blower motors are of which type?

A) direct drive
B) belt drive
C) neither a nor b
D) both a and b

Question 17

Which of the following is NOT a condition of a belt on a blower motor being too loose?

A) reduced air flow
B) belt slippage
C) excessive noise
D) motor overheating

Question 18

Which of the following is a condition of an air conditioning system that is undercharged?

A) increased possibility of floodback to the compressor
B) higher operating pressures
C) low operating pressures
D) reduced evaporator superheat

Question 19

If, while troubleshooting an R-22 residential air conditioning system at near design conditions, the operating pressures are found to be 80 psig on the low side and 200 psig on the high side, it is most likely that the system is opperating

A) with a compressor that has leaking valves
B) with a rerigerant overcharge
C) with an overfeeding metering device
D) properly

Question 20

Residential air conditioning systems have a superheat range of __________ degrees under normal operating conditions.

A) 8 to 12
B) 6 to 10
C) 10 to 15
D) 1 to 5

Question 21

List three common ways by which air can find its way into an air conditioning system.

Question 22

List four possible fan motor mechanical problems.

Question 23

Newer, high efficiency air conditioning systems operate with __________ condenser saturation temperatures and pressures than older, standard efficiency systems.

A) higher
B) lower

Question 24

Arrange the following troubleshooting steps in the correct order.
_____ test the system operation
_____ gather information
_____ verify the complaint
_____ complete the service call
_____ perform a visual inspection
_____ isolate the problem
_____ correct the problem

Question 25

List three key indicators that pulleys are not aligned properly on blowers.

Question 26

Halide leak detectors will work only with __________ refrigerants.