Commercial Refrigeration Test Chapter
8, 9 Exam Questions and Answers
How do you charge an R134a refrigerator with a cap tube system? - Answer-Weigh in
the charge per the nameplate.
What is the best thing to do before evacuating a refrigeration system? - Answer-
Evacuate the gauge and pump connections to ensure all connections are tight.
If a micron gauge is not working properly, what is the first thing to do to correct it? -
Answer-Pour alcohol into the inlet port to clean oil out of it.
In the "real world" how often is it practical to replace the oil in a vacuum pump? -
Answer-Vacuum pumps must always have their oil changed after each use.
What precautions should be taken when charging liquid through the suction service
valve? - Answer-Restrict the flow of liquid if the amperage is above 10% of RLA or the
valve frosts
What are some of the considerations when charging refrigerant into the system high
side? - Answer-The unit capacity is over 5 pounds, in a vacuum, and the compressor is
off.
Why is the compressor started in the 2nd part of a triple evacuation? - Answer-To
release moisture that may be trapped in the oil.
Which of the following will damage a 3Ø motor? - Answer-Loss of phase or a voltage
imbalance over 2%.
If you need a 30 amp compressor contactor, which of the following is the best choice -
Answer-30 amp inductive - 20 amp resistive
The incoming voltage to a contactor is 240 and the voltage leaving is 235. What is the
proper corrective action necessary? - Answer-Replace the contacts or the contactor.
Why are starting components needed on a 1Ø compressor motor? - Answer-Single
phase motors need a phase shift in order to start the rotor turning.
The proper wiring sequence for a potential relay is: - Answer-5 (common), 2 (start), 1
(run)
When troubleshooting a potential relay, the terminals 5, 2, and 1 refer to: - Answer-.5
and 2 are the coil, 1 and 2 are the relay contacts.
8, 9 Exam Questions and Answers
How do you charge an R134a refrigerator with a cap tube system? - Answer-Weigh in
the charge per the nameplate.
What is the best thing to do before evacuating a refrigeration system? - Answer-
Evacuate the gauge and pump connections to ensure all connections are tight.
If a micron gauge is not working properly, what is the first thing to do to correct it? -
Answer-Pour alcohol into the inlet port to clean oil out of it.
In the "real world" how often is it practical to replace the oil in a vacuum pump? -
Answer-Vacuum pumps must always have their oil changed after each use.
What precautions should be taken when charging liquid through the suction service
valve? - Answer-Restrict the flow of liquid if the amperage is above 10% of RLA or the
valve frosts
What are some of the considerations when charging refrigerant into the system high
side? - Answer-The unit capacity is over 5 pounds, in a vacuum, and the compressor is
off.
Why is the compressor started in the 2nd part of a triple evacuation? - Answer-To
release moisture that may be trapped in the oil.
Which of the following will damage a 3Ø motor? - Answer-Loss of phase or a voltage
imbalance over 2%.
If you need a 30 amp compressor contactor, which of the following is the best choice -
Answer-30 amp inductive - 20 amp resistive
The incoming voltage to a contactor is 240 and the voltage leaving is 235. What is the
proper corrective action necessary? - Answer-Replace the contacts or the contactor.
Why are starting components needed on a 1Ø compressor motor? - Answer-Single
phase motors need a phase shift in order to start the rotor turning.
The proper wiring sequence for a potential relay is: - Answer-5 (common), 2 (start), 1
(run)
When troubleshooting a potential relay, the terminals 5, 2, and 1 refer to: - Answer-.5
and 2 are the coil, 1 and 2 are the relay contacts.
