AZ L-39 Air Conditioning & Refrigeration
Contractor Exam Questions And Correct
Answers (Verified Answers) Plus
Rationale2026 Q&A| Instant Download
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1. What is the primary function of a refrigeration system?
A. Heat a building
B. Remove heat from a space
C. Generate electricity
D. Increase humidity
Answer: B
Rationale: Refrigeration systems are designed to remove heat from a
space to lower the temperature.
2. Which refrigerant has zero ozone depletion potential (ODP)?
A. R-12
B. R-22
C. R-410A
D. R-502
Answer: C
Rationale: R-410A is a hydrofluorocarbon (HFC) with zero ODP,
making it environmentally safer than older CFCs and HCFCs.
3. The purpose of the expansion valve in a refrigeration cycle is to:
A. Compress refrigerant
B. Condense refrigerant
C. Regulate refrigerant flow into the evaporator
D. Remove moisture
Answer: C
, Rationale: The expansion valve meters refrigerant into the
evaporator at the proper pressure and flow rate.
4. What type of compressor is commonly used in residential air
conditioning?
A. Reciprocating
B. Scroll
C. Screw
D. Centrifugal
Answer: B
Rationale: Scroll compressors are efficient, quiet, and reliable,
making them ideal for residential HVAC systems.
5. Superheat is measured at which part of the system?
A. Compressor suction line
B. Evaporator outlet
C. Condenser inlet
D. Expansion valve inlet
Answer: B
Rationale: Superheat is the temperature above the refrigerant’s
boiling point measured at the evaporator outlet to ensure complete
vaporization.
6. Subcooling refers to:
A. Heating refrigerant
B. Cooling refrigerant below its condensing temperature
C. Freezing the evaporator
D. Increasing pressure in suction line
Answer: B
Rationale: Subcooling ensures refrigerant is fully condensed before
entering the expansion valve.
7. The standard refrigerant used in new residential systems in the U.S. is:
A. R-12
B. R-22
C. R-410A
D. R-502
Answer: C
Rationale: R-410A replaced R-22 due to environmental regulations
prohibiting ozone-depleting refrigerants.
, 8. Which of the following is a common sign of a refrigerant leak?
A. Increased cooling efficiency
B. Ice formation on the evaporator coil
C. High suction pressure
D. Warm air from supply vents
Answer: B
Rationale: Low refrigerant causes reduced evaporation temperature,
leading to ice formation on the evaporator coil.
9. The SEER rating measures:
A. Heating efficiency
B. Electrical load
C. Cooling efficiency
D. Airflow velocity
Answer: C
Rationale: SEER (Seasonal Energy Efficiency Ratio) indicates the
efficiency of air conditioning systems over a typical cooling season.
10. What is the function of the condenser in a refrigeration system?
A. Absorb heat
B. Increase refrigerant velocity
C. Release heat to the surrounding air
D. Compress refrigerant
Answer: C
Rationale: The condenser removes heat from the refrigerant,
allowing it to condense from a gas to a liquid.
11. Which type of refrigerant oil is commonly used with R-410A
systems?
A. Mineral oil
B. Polyol ester (POE) oil
C. Alkylbenzene oil
D. Silicone oil
Answer: B
Rationale: POE oils are compatible with R-410A and synthetic
refrigerants due to solubility and lubrication properties.
12. Which device protects compressors from excessive current?
A. Expansion valve
B. Thermostat
C. Overload protector
Contractor Exam Questions And Correct
Answers (Verified Answers) Plus
Rationale2026 Q&A| Instant Download
1. What is the primary function of a refrigeration system?
A. Heat a building
B. Remove heat from a space
C. Generate electricity
D. Increase humidity
Answer: B
Rationale: Refrigeration systems are designed to remove heat from a
space to lower the temperature.
2. Which refrigerant has zero ozone depletion potential (ODP)?
A. R-12
B. R-22
C. R-410A
D. R-502
Answer: C
Rationale: R-410A is a hydrofluorocarbon (HFC) with zero ODP,
making it environmentally safer than older CFCs and HCFCs.
3. The purpose of the expansion valve in a refrigeration cycle is to:
A. Compress refrigerant
B. Condense refrigerant
C. Regulate refrigerant flow into the evaporator
D. Remove moisture
Answer: C
, Rationale: The expansion valve meters refrigerant into the
evaporator at the proper pressure and flow rate.
4. What type of compressor is commonly used in residential air
conditioning?
A. Reciprocating
B. Scroll
C. Screw
D. Centrifugal
Answer: B
Rationale: Scroll compressors are efficient, quiet, and reliable,
making them ideal for residential HVAC systems.
5. Superheat is measured at which part of the system?
A. Compressor suction line
B. Evaporator outlet
C. Condenser inlet
D. Expansion valve inlet
Answer: B
Rationale: Superheat is the temperature above the refrigerant’s
boiling point measured at the evaporator outlet to ensure complete
vaporization.
6. Subcooling refers to:
A. Heating refrigerant
B. Cooling refrigerant below its condensing temperature
C. Freezing the evaporator
D. Increasing pressure in suction line
Answer: B
Rationale: Subcooling ensures refrigerant is fully condensed before
entering the expansion valve.
7. The standard refrigerant used in new residential systems in the U.S. is:
A. R-12
B. R-22
C. R-410A
D. R-502
Answer: C
Rationale: R-410A replaced R-22 due to environmental regulations
prohibiting ozone-depleting refrigerants.
, 8. Which of the following is a common sign of a refrigerant leak?
A. Increased cooling efficiency
B. Ice formation on the evaporator coil
C. High suction pressure
D. Warm air from supply vents
Answer: B
Rationale: Low refrigerant causes reduced evaporation temperature,
leading to ice formation on the evaporator coil.
9. The SEER rating measures:
A. Heating efficiency
B. Electrical load
C. Cooling efficiency
D. Airflow velocity
Answer: C
Rationale: SEER (Seasonal Energy Efficiency Ratio) indicates the
efficiency of air conditioning systems over a typical cooling season.
10. What is the function of the condenser in a refrigeration system?
A. Absorb heat
B. Increase refrigerant velocity
C. Release heat to the surrounding air
D. Compress refrigerant
Answer: C
Rationale: The condenser removes heat from the refrigerant,
allowing it to condense from a gas to a liquid.
11. Which type of refrigerant oil is commonly used with R-410A
systems?
A. Mineral oil
B. Polyol ester (POE) oil
C. Alkylbenzene oil
D. Silicone oil
Answer: B
Rationale: POE oils are compatible with R-410A and synthetic
refrigerants due to solubility and lubrication properties.
12. Which device protects compressors from excessive current?
A. Expansion valve
B. Thermostat
C. Overload protector
