CO Refrigeration Contractor Exam
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A| Instant Download Pdf
1. Which of the following refrigerants has zero ozone depletion potential
(ODP)?
A. R-12
B. R-22
C. R-410A
D. R-502
R-410A is a hydrofluorocarbon (HFC) refrigerant with zero ozone
depletion potential, making it safer for the environment.
2. What is the main purpose of a compressor in a refrigeration system?
A. Condense the refrigerant
B. Increase refrigerant pressure and circulate it through the system
C. Evaporate the refrigerant
D. Filter impurities from the refrigerant
The compressor raises the pressure of the refrigerant and forces it
through the system, enabling heat transfer.
3. Which type of expansion device uses a fixed orifice to control
refrigerant flow?
A. Thermostatic expansion valve
B. Capillary tube
C. Electronic expansion valve
D. Solenoid valve
A capillary tube is a fixed-size small-diameter tube that restricts
refrigerant flow, causing a pressure drop before the evaporator.
4. What is the function of the condenser in a refrigeration system?
A. Absorb heat from the space being cooled
B. Release heat from the refrigerant to the surrounding air or
, water
C. Increase refrigerant velocity
D. Store excess refrigerant
The condenser removes heat from the high-pressure refrigerant
vapor, turning it into liquid.
5. Superheat is measured at which point in a refrigeration system?
A. After the condenser
B. At the evaporator outlet
C. Before the compressor
D. After the expansion device
Superheat is the temperature of vapor above its boiling point at the
evaporator exit, ensuring no liquid enters the compressor.
6. What is the effect of low refrigerant charge on a system?
A. Reduced cooling capacity
B. Increased condenser pressure
C. Increased energy efficiency
D. No effect
Low refrigerant reduces heat absorption in the evaporator, lowering
cooling performance.
7. Which of the following is a common refrigerant in commercial
refrigeration?
A. R-134a
B. R-404A
C. R-22
D. R-502
R-404A is widely used in commercial refrigeration due to its
favorable thermodynamic properties.
8. What device is used to prevent liquid refrigerant from entering the
compressor?
A. Condenser fan
B. Receiver
C. Accumulator
D. Sight glass
The accumulator collects excess liquid refrigerant at the evaporator
exit, protecting the compressor.
9. What is the purpose of oil in a refrigeration system?
A. Cool the condenser
, B. Lubricate moving parts of the compressor
C. Increase refrigerant flow
D. Insulate the piping
Oil reduces friction and wear in the compressor, prolonging its
lifespan.
10. A refrigeration system is operating with high head pressure.
Which of the following is a likely cause?
A. Low ambient temperature
B. Dirty or blocked condenser
C. Low refrigerant charge
D. All of the above
High head pressure can result from low airflow, dirty coils,
overcharge, or high ambient temperatures.
11. In a direct expansion system, the refrigerant absorbs heat in the:
A. Condenser
B. Receiver
C. Evaporator
D. Compressor
The evaporator is where the refrigerant absorbs heat from the space
being cooled.
12. What is the primary purpose of the expansion device?
A. Increase refrigerant pressure
B. Reduce refrigerant pressure to allow evaporation
C. Heat refrigerant
D. Lubricate the compressor
The expansion device reduces pressure, allowing the refrigerant to
boil at a lower temperature.
13. Which pressure is considered the “low side” of a refrigeration
system?
A. Compressor discharge
B. Condenser inlet
C. Evaporator pressure
D. Liquid line pressure
The low side is the portion of the system where the refrigerant is
evaporating and at low pressure.
14. A liquid line filter-drier is installed to:
A. Increase system pressure
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A| Instant Download Pdf
1. Which of the following refrigerants has zero ozone depletion potential
(ODP)?
A. R-12
B. R-22
C. R-410A
D. R-502
R-410A is a hydrofluorocarbon (HFC) refrigerant with zero ozone
depletion potential, making it safer for the environment.
2. What is the main purpose of a compressor in a refrigeration system?
A. Condense the refrigerant
B. Increase refrigerant pressure and circulate it through the system
C. Evaporate the refrigerant
D. Filter impurities from the refrigerant
The compressor raises the pressure of the refrigerant and forces it
through the system, enabling heat transfer.
3. Which type of expansion device uses a fixed orifice to control
refrigerant flow?
A. Thermostatic expansion valve
B. Capillary tube
C. Electronic expansion valve
D. Solenoid valve
A capillary tube is a fixed-size small-diameter tube that restricts
refrigerant flow, causing a pressure drop before the evaporator.
4. What is the function of the condenser in a refrigeration system?
A. Absorb heat from the space being cooled
B. Release heat from the refrigerant to the surrounding air or
, water
C. Increase refrigerant velocity
D. Store excess refrigerant
The condenser removes heat from the high-pressure refrigerant
vapor, turning it into liquid.
5. Superheat is measured at which point in a refrigeration system?
A. After the condenser
B. At the evaporator outlet
C. Before the compressor
D. After the expansion device
Superheat is the temperature of vapor above its boiling point at the
evaporator exit, ensuring no liquid enters the compressor.
6. What is the effect of low refrigerant charge on a system?
A. Reduced cooling capacity
B. Increased condenser pressure
C. Increased energy efficiency
D. No effect
Low refrigerant reduces heat absorption in the evaporator, lowering
cooling performance.
7. Which of the following is a common refrigerant in commercial
refrigeration?
A. R-134a
B. R-404A
C. R-22
D. R-502
R-404A is widely used in commercial refrigeration due to its
favorable thermodynamic properties.
8. What device is used to prevent liquid refrigerant from entering the
compressor?
A. Condenser fan
B. Receiver
C. Accumulator
D. Sight glass
The accumulator collects excess liquid refrigerant at the evaporator
exit, protecting the compressor.
9. What is the purpose of oil in a refrigeration system?
A. Cool the condenser
, B. Lubricate moving parts of the compressor
C. Increase refrigerant flow
D. Insulate the piping
Oil reduces friction and wear in the compressor, prolonging its
lifespan.
10. A refrigeration system is operating with high head pressure.
Which of the following is a likely cause?
A. Low ambient temperature
B. Dirty or blocked condenser
C. Low refrigerant charge
D. All of the above
High head pressure can result from low airflow, dirty coils,
overcharge, or high ambient temperatures.
11. In a direct expansion system, the refrigerant absorbs heat in the:
A. Condenser
B. Receiver
C. Evaporator
D. Compressor
The evaporator is where the refrigerant absorbs heat from the space
being cooled.
12. What is the primary purpose of the expansion device?
A. Increase refrigerant pressure
B. Reduce refrigerant pressure to allow evaporation
C. Heat refrigerant
D. Lubricate the compressor
The expansion device reduces pressure, allowing the refrigerant to
boil at a lower temperature.
13. Which pressure is considered the “low side” of a refrigeration
system?
A. Compressor discharge
B. Condenser inlet
C. Evaporator pressure
D. Liquid line pressure
The low side is the portion of the system where the refrigerant is
evaporating and at low pressure.
14. A liquid line filter-drier is installed to:
A. Increase system pressure
