Idaho Refrigeration Contractor
Qualification Advanced 100-Question
Practice Exam 2026 | Questions &
Answers with Detailed Rationales |
Complete Exam Prep & Study Guide
1. In a refrigeration system, what is the primary function of the compressor?
A. Absorb heat from the conditioned space
B. Reject heat directly to the atmosphere
C. Raise the refrigerant vapor pressure and temperature so heat can be rejected
at the condenser
D. Reduce liquid refrigerant pressure
Answer: Raise the refrigerant vapor pressure and temperature so heat can be
rejected at the condenser
Rationale: The compressor raises the pressure and corresponding saturation
temperature of the refrigerant vapor, allowing the condenser to reject absorbed
and compression-added heat to a medium at a lower temperature.
2. A refrigeration system has a high condensing pressure and a relatively high
liquid-line temperature. Which condition is most likely?
,A. Low outdoor temperature with excessive subcooling
B. Insufficient condenser heat rejection
C. Excessive evaporator airflow
D. Low compressor discharge temperature
Answer: Insufficient condenser heat rejection
Rationale: A dirty condenser, inadequate airflow, excessive ambient
temperature, or noncondensable gases can reduce condenser heat rejection and
increase condensing pressure and liquid temperature.
3. What is the principal purpose of superheat at the evaporator outlet?
A. Prevent liquid from entering the condenser
B. Increase condenser capacity
C. Ensure predominantly vapor refrigerant enters the compressor
D. Keep the liquid receiver full
Answer: Ensure predominantly vapor refrigerant enters the compressor
Rationale: Adequate suction superheat helps prevent liquid refrigerant from
returning to the compressor, reducing the risk of liquid slugging and oil dilution.
4. A thermostatic expansion valve is hunting significantly. Which condition can
contribute to this problem?
A. Correctly sized sensing bulb
B. Stable load
C. Improper valve sizing or unstable system conditions
D. Proper refrigerant charge
Answer: Improper valve sizing or unstable system conditions
Rationale: An oversized TXV, incorrect sensing-bulb installation, excessive
pressure drop, or changing load conditions can produce unstable valve
operation and fluctuating superheat.
, 5. What does subcooling indicate in a properly operating refrigeration
system?
A. The amount of vapor in the evaporator
B. The temperature reduction of liquid refrigerant below its saturation
temperature at a given pressure
C. Compressor compression ratio
D. Evaporator approach temperature
Answer: The temperature reduction of liquid refrigerant below its saturation
temperature at a given pressure
Rationale: Subcooling confirms that liquid refrigerant has been cooled below its
saturation temperature, which helps prevent flashing before the metering
device.
6. What is the most appropriate location for a TXV sensing bulb on a
conventional horizontal suction line?
A. Bottom of the pipe
B. Inside the evaporator
C. Properly secured to the suction line in accordance with the valve
manufacturer's instructions, generally on the upper side of the horizontal pipe
D. On the liquid line
Answer: Properly secured to the suction line in accordance with the valve
manufacturer's instructions, generally on the upper side of the horizontal pipe
Rationale: The bulb must sense representative suction-line temperature and be
installed securely and insulated as required by the manufacturer.
7. What is the primary purpose of a liquid receiver?
A. Store compressor oil
B. Store liquid refrigerant and accommodate changes in system charge
C. Remove moisture from the refrigerant
D. Increase evaporator superheat
, Answer: Store liquid refrigerant and accommodate changes in system charge
Rationale: A receiver provides controlled liquid storage, particularly in systems
using a TXV or systems where refrigerant inventory varies with operating
conditions.
8. Why is a filter-drier installed in a refrigeration liquid line?
A. To increase suction pressure
B. To eliminate compressor vibration
C. To remove moisture, acids, and contaminants from the refrigerant circuit
D. To raise evaporator temperature
Answer: To remove moisture, acids, and contaminants from the refrigerant
circuit
Rationale: Moisture and contaminants can cause corrosion, acid formation,
metering-device blockage, and compressor damage.
9. What is the best indication that a liquid-line filter-drier is becoming
restricted?
A. Low pressure drop across the drier
B. A measurable temperature drop across the drier under stable operating
conditions
C. High suction pressure caused by flooding
D. Increased evaporator airflow
Answer: A measurable temperature drop across the drier under stable operating
conditions
Rationale: A significant temperature difference across a liquid-line drier can
indicate pressure drop and restriction, although manufacturer specifications and
operating conditions must be considered.
10.Why should a refrigeration system be evacuated before charging?
Qualification Advanced 100-Question
Practice Exam 2026 | Questions &
Answers with Detailed Rationales |
Complete Exam Prep & Study Guide
1. In a refrigeration system, what is the primary function of the compressor?
A. Absorb heat from the conditioned space
B. Reject heat directly to the atmosphere
C. Raise the refrigerant vapor pressure and temperature so heat can be rejected
at the condenser
D. Reduce liquid refrigerant pressure
Answer: Raise the refrigerant vapor pressure and temperature so heat can be
rejected at the condenser
Rationale: The compressor raises the pressure and corresponding saturation
temperature of the refrigerant vapor, allowing the condenser to reject absorbed
and compression-added heat to a medium at a lower temperature.
2. A refrigeration system has a high condensing pressure and a relatively high
liquid-line temperature. Which condition is most likely?
,A. Low outdoor temperature with excessive subcooling
B. Insufficient condenser heat rejection
C. Excessive evaporator airflow
D. Low compressor discharge temperature
Answer: Insufficient condenser heat rejection
Rationale: A dirty condenser, inadequate airflow, excessive ambient
temperature, or noncondensable gases can reduce condenser heat rejection and
increase condensing pressure and liquid temperature.
3. What is the principal purpose of superheat at the evaporator outlet?
A. Prevent liquid from entering the condenser
B. Increase condenser capacity
C. Ensure predominantly vapor refrigerant enters the compressor
D. Keep the liquid receiver full
Answer: Ensure predominantly vapor refrigerant enters the compressor
Rationale: Adequate suction superheat helps prevent liquid refrigerant from
returning to the compressor, reducing the risk of liquid slugging and oil dilution.
4. A thermostatic expansion valve is hunting significantly. Which condition can
contribute to this problem?
A. Correctly sized sensing bulb
B. Stable load
C. Improper valve sizing or unstable system conditions
D. Proper refrigerant charge
Answer: Improper valve sizing or unstable system conditions
Rationale: An oversized TXV, incorrect sensing-bulb installation, excessive
pressure drop, or changing load conditions can produce unstable valve
operation and fluctuating superheat.
, 5. What does subcooling indicate in a properly operating refrigeration
system?
A. The amount of vapor in the evaporator
B. The temperature reduction of liquid refrigerant below its saturation
temperature at a given pressure
C. Compressor compression ratio
D. Evaporator approach temperature
Answer: The temperature reduction of liquid refrigerant below its saturation
temperature at a given pressure
Rationale: Subcooling confirms that liquid refrigerant has been cooled below its
saturation temperature, which helps prevent flashing before the metering
device.
6. What is the most appropriate location for a TXV sensing bulb on a
conventional horizontal suction line?
A. Bottom of the pipe
B. Inside the evaporator
C. Properly secured to the suction line in accordance with the valve
manufacturer's instructions, generally on the upper side of the horizontal pipe
D. On the liquid line
Answer: Properly secured to the suction line in accordance with the valve
manufacturer's instructions, generally on the upper side of the horizontal pipe
Rationale: The bulb must sense representative suction-line temperature and be
installed securely and insulated as required by the manufacturer.
7. What is the primary purpose of a liquid receiver?
A. Store compressor oil
B. Store liquid refrigerant and accommodate changes in system charge
C. Remove moisture from the refrigerant
D. Increase evaporator superheat
, Answer: Store liquid refrigerant and accommodate changes in system charge
Rationale: A receiver provides controlled liquid storage, particularly in systems
using a TXV or systems where refrigerant inventory varies with operating
conditions.
8. Why is a filter-drier installed in a refrigeration liquid line?
A. To increase suction pressure
B. To eliminate compressor vibration
C. To remove moisture, acids, and contaminants from the refrigerant circuit
D. To raise evaporator temperature
Answer: To remove moisture, acids, and contaminants from the refrigerant
circuit
Rationale: Moisture and contaminants can cause corrosion, acid formation,
metering-device blockage, and compressor damage.
9. What is the best indication that a liquid-line filter-drier is becoming
restricted?
A. Low pressure drop across the drier
B. A measurable temperature drop across the drier under stable operating
conditions
C. High suction pressure caused by flooding
D. Increased evaporator airflow
Answer: A measurable temperature drop across the drier under stable operating
conditions
Rationale: A significant temperature difference across a liquid-line drier can
indicate pressure drop and restriction, although manufacturer specifications and
operating conditions must be considered.
10.Why should a refrigeration system be evacuated before charging?
