HVAC Unit 25 Special Refrigeration
System Components Review Exam
Questions and Answers
Which is not a basic component of the compression refrigeration cycle? - Answer-D)
Suction Filter pg 509
Describe modulating fluid flow - Answer-Modulating fluid flow is throttling the amount of
fluid through a gas line. Controlling the flow between maximum or no flow. pg 510
The purpose of the crankcase pressure-regulating valve is to - Answer-D) prevent a
compressor overload condition pg 513
Describe the function of the electric evaporator pressure-regulating valve (EEPR) -
Answer-They provide very close temperature control of the discharge air in supermarket
display cases. They can move in very small increments to either open or close the
suction line in response to the refrigerated cases discharge air temperatures. pg 512
What are three main reasons why automatic pump-down systems are used on
refrigeration systems? - Answer-1. To rid the evaporator, suction line ,and crankcase of
refrigerant before the off cycle and defrost cycle so migration of refrigerant to the
compressor and or compressor crankcase cannot occur.
2. To prevent surges of liquid refrigerant from entering the suction port of the
compressor (slugging) during start-ups.
3. To rid the crankcase of refrigerant to prevent oil from foaming during start-ups and
lubrication from being robbed from the compressor's mechanical parts. pg 523
Briefly describe the function of a non-short-cycling or one-time automatic pump-down
system - Answer-The only way for the refrigeration system to go out of pump-down is if
the thermostat calls for cooling. pg 522
Two types of relief valves are _______ and _______ - Answer-spring loaded, one-time
Why is low-ambient control necessary? - Answer-It is needed for refrigeration that is
used all year long. In the winter, the head pressure will go down to the point that the
expansion valve will not have enough pressure drop across it to feed refrigerant
correctly.
Which is not a method of low-ambient control on air-cooled equipment? - Answer-A)
Modulating TXV
Describe low-pressure switch - Answer-It is a device that provides low-charge protection
and it also provides control of space temperature. For low-charge protection, the low
System Components Review Exam
Questions and Answers
Which is not a basic component of the compression refrigeration cycle? - Answer-D)
Suction Filter pg 509
Describe modulating fluid flow - Answer-Modulating fluid flow is throttling the amount of
fluid through a gas line. Controlling the flow between maximum or no flow. pg 510
The purpose of the crankcase pressure-regulating valve is to - Answer-D) prevent a
compressor overload condition pg 513
Describe the function of the electric evaporator pressure-regulating valve (EEPR) -
Answer-They provide very close temperature control of the discharge air in supermarket
display cases. They can move in very small increments to either open or close the
suction line in response to the refrigerated cases discharge air temperatures. pg 512
What are three main reasons why automatic pump-down systems are used on
refrigeration systems? - Answer-1. To rid the evaporator, suction line ,and crankcase of
refrigerant before the off cycle and defrost cycle so migration of refrigerant to the
compressor and or compressor crankcase cannot occur.
2. To prevent surges of liquid refrigerant from entering the suction port of the
compressor (slugging) during start-ups.
3. To rid the crankcase of refrigerant to prevent oil from foaming during start-ups and
lubrication from being robbed from the compressor's mechanical parts. pg 523
Briefly describe the function of a non-short-cycling or one-time automatic pump-down
system - Answer-The only way for the refrigeration system to go out of pump-down is if
the thermostat calls for cooling. pg 522
Two types of relief valves are _______ and _______ - Answer-spring loaded, one-time
Why is low-ambient control necessary? - Answer-It is needed for refrigeration that is
used all year long. In the winter, the head pressure will go down to the point that the
expansion valve will not have enough pressure drop across it to feed refrigerant
correctly.
Which is not a method of low-ambient control on air-cooled equipment? - Answer-A)
Modulating TXV
Describe low-pressure switch - Answer-It is a device that provides low-charge protection
and it also provides control of space temperature. For low-charge protection, the low
