CO Refrigeration Contractor Exam
Practice Questions And Correct
Answers (Verified Answers) Plus
Rationale 2027 Q&A| Instant
Download Pdf.
1. A refrigeration contractor is troubleshooting a low-temperature
commercial refrigeration system that has a properly charged
refrigerant circuit but exhibits high condensing pressure and
elevated compressor discharge temperature. The evaporator load is
normal, the condenser fan is operating, and the condenser coil is
visibly contaminated with debris. Which condition is the most likely
primary cause of the symptoms?
A. Excessive evaporator superheat caused by an oversized expansion valve
B. Restricted airflow across the condenser causing inadequate heat
rejection
C. Low suction pressure caused by excessive condenser airflow
D. Refrigerant migration caused by an oversized receiver
B. Restricted airflow across the condenser causing inadequate heat
rejection
,A dirty or obstructed condenser reduces heat transfer to the surrounding
air, causing condensing pressure and discharge temperature to rise.
Correcting condenser airflow and cleaning the heat-transfer surfaces
should be part of the diagnostic procedure.
2. In a vapor-compression refrigeration cycle, what is the primary
function of the compressor?
A. Reduce the temperature of liquid refrigerant before expansion
B. Convert high-pressure liquid refrigerant into low-pressure vapor
C. Raise the pressure and temperature of refrigerant vapor and move it
through the system
D. Remove moisture from the refrigerant circuit
C. Raise the pressure and temperature of refrigerant vapor and move it
through the system
The compressor receives relatively low-pressure vapor from the
evaporator and compresses it into high-pressure, high-temperature
vapor for delivery to the condenser.
3. A refrigeration technician measures suction pressure and discharge
pressure but wants to determine whether the evaporator is
receiving the proper amount of refrigerant at the outlet. Which
measurement is most useful?
A. Subcooling
B. Superheat
,C. Condenser approach temperature
D. Compressor amperage alone
B. Superheat
Evaporator superheat indicates how much the refrigerant vapor
temperature exceeds its saturation temperature at the measured
suction pressure. It is an important diagnostic measurement for
evaluating evaporator refrigerant feeding and preventing liquid from
returning to the compressor.
4. What is the primary purpose of an expansion valve in a refrigeration
system?
A. Increase refrigerant pressure before entering the condenser
B. Control refrigerant flow into the evaporator while producing a pressure
drop
C. Remove noncondensable gases from the condenser
D. Increase compressor discharge temperature
B. Control refrigerant flow into the evaporator while producing a
pressure drop
The expansion device meters refrigerant into the evaporator and
reduces its pressure, allowing part of the liquid refrigerant to flash into
vapor and lowering its saturation temperature.
5. A refrigeration system has unusually low suction pressure, high
superheat, and a starved evaporator. The liquid-line sight glass
, shows bubbles, and the system has no obvious compressor
malfunction. Which condition should be investigated first?
A. Excessive refrigerant charge
B. Insufficient refrigerant supply to the expansion device
C. Excessively high condenser airflow
D. Excessively low superheat
B. Insufficient refrigerant supply to the expansion device
A starved evaporator accompanied by low suction pressure and high
superheat commonly indicates inadequate refrigerant flow, which may
result from low charge, a restriction, or a malfunctioning metering
device.
6. What is the principal purpose of a liquid receiver installed in a
refrigeration system?
A. Store excess liquid refrigerant and provide a controlled liquid supply to
the metering device
B. Remove oil from compressor discharge gas
C. Increase evaporator pressure
D. Convert liquid refrigerant into superheated vapor
A. Store excess liquid refrigerant and provide a controlled liquid supply
to the metering device
A receiver provides a reservoir for liquid refrigerant, allowing the system
to accommodate changes in operating conditions and refrigerant
Practice Questions And Correct
Answers (Verified Answers) Plus
Rationale 2027 Q&A| Instant
Download Pdf.
1. A refrigeration contractor is troubleshooting a low-temperature
commercial refrigeration system that has a properly charged
refrigerant circuit but exhibits high condensing pressure and
elevated compressor discharge temperature. The evaporator load is
normal, the condenser fan is operating, and the condenser coil is
visibly contaminated with debris. Which condition is the most likely
primary cause of the symptoms?
A. Excessive evaporator superheat caused by an oversized expansion valve
B. Restricted airflow across the condenser causing inadequate heat
rejection
C. Low suction pressure caused by excessive condenser airflow
D. Refrigerant migration caused by an oversized receiver
B. Restricted airflow across the condenser causing inadequate heat
rejection
,A dirty or obstructed condenser reduces heat transfer to the surrounding
air, causing condensing pressure and discharge temperature to rise.
Correcting condenser airflow and cleaning the heat-transfer surfaces
should be part of the diagnostic procedure.
2. In a vapor-compression refrigeration cycle, what is the primary
function of the compressor?
A. Reduce the temperature of liquid refrigerant before expansion
B. Convert high-pressure liquid refrigerant into low-pressure vapor
C. Raise the pressure and temperature of refrigerant vapor and move it
through the system
D. Remove moisture from the refrigerant circuit
C. Raise the pressure and temperature of refrigerant vapor and move it
through the system
The compressor receives relatively low-pressure vapor from the
evaporator and compresses it into high-pressure, high-temperature
vapor for delivery to the condenser.
3. A refrigeration technician measures suction pressure and discharge
pressure but wants to determine whether the evaporator is
receiving the proper amount of refrigerant at the outlet. Which
measurement is most useful?
A. Subcooling
B. Superheat
,C. Condenser approach temperature
D. Compressor amperage alone
B. Superheat
Evaporator superheat indicates how much the refrigerant vapor
temperature exceeds its saturation temperature at the measured
suction pressure. It is an important diagnostic measurement for
evaluating evaporator refrigerant feeding and preventing liquid from
returning to the compressor.
4. What is the primary purpose of an expansion valve in a refrigeration
system?
A. Increase refrigerant pressure before entering the condenser
B. Control refrigerant flow into the evaporator while producing a pressure
drop
C. Remove noncondensable gases from the condenser
D. Increase compressor discharge temperature
B. Control refrigerant flow into the evaporator while producing a
pressure drop
The expansion device meters refrigerant into the evaporator and
reduces its pressure, allowing part of the liquid refrigerant to flash into
vapor and lowering its saturation temperature.
5. A refrigeration system has unusually low suction pressure, high
superheat, and a starved evaporator. The liquid-line sight glass
, shows bubbles, and the system has no obvious compressor
malfunction. Which condition should be investigated first?
A. Excessive refrigerant charge
B. Insufficient refrigerant supply to the expansion device
C. Excessively high condenser airflow
D. Excessively low superheat
B. Insufficient refrigerant supply to the expansion device
A starved evaporator accompanied by low suction pressure and high
superheat commonly indicates inadequate refrigerant flow, which may
result from low charge, a restriction, or a malfunctioning metering
device.
6. What is the principal purpose of a liquid receiver installed in a
refrigeration system?
A. Store excess liquid refrigerant and provide a controlled liquid supply to
the metering device
B. Remove oil from compressor discharge gas
C. Increase evaporator pressure
D. Convert liquid refrigerant into superheated vapor
A. Store excess liquid refrigerant and provide a controlled liquid supply
to the metering device
A receiver provides a reservoir for liquid refrigerant, allowing the system
to accommodate changes in operating conditions and refrigerant
