Alabama Heating and Air Conditioning
Contractor Exam Practice Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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1. Which refrigerant property is most directly responsible for absorbing
heat in the evaporator?
A. High density
B. High viscosity
C. Latent heat of vaporization
D. Low molecular weight
Rationale: Refrigerants absorb large amounts of heat during the phase
change from liquid to vapor. This latent heat of vaporization is the primary
mechanism by which cooling occurs in the evaporator.
2. What is the primary purpose of the compressor in a vapor-
compression refrigeration system?
,A. Condense refrigerant
B. Remove moisture
C. Raise refrigerant pressure and circulate refrigerant
D. Meter refrigerant flow
Rationale: The compressor increases refrigerant pressure and temperature
while circulating refrigerant throughout the system, enabling the
refrigeration cycle to continue.
3. Which component meters refrigerant into the evaporator?
A. Compressor
B. Condenser
C. Expansion valve
D. Accumulator
Rationale: The expansion valve controls refrigerant flow into the
evaporator while reducing pressure, allowing the refrigerant to boil and
absorb heat.
4. Superheat is best defined as:
A. Heat removed by the condenser
B. Temperature above the refrigerant's saturation temperature
C. Difference between indoor and outdoor temperatures
D. Compressor discharge temperature
,Rationale: Superheat measures how much the refrigerant vapor
temperature exceeds its saturation temperature, ensuring only vapor
enters the compressor.
5. Subcooling refers to:
A. Cooling air below freezing
B. Heating refrigerant above saturation
C. Cooling liquid refrigerant below its saturation temperature
D. Reducing compressor temperature
Rationale: Subcooling ensures liquid refrigerant reaches the metering
device without flashing into vapor prematurely.
6. Which refrigerant has a low ozone depletion potential and is
commonly used in modern residential systems?
A. R-22
B. R-410A
C. R-12
D. R-11
Rationale: R-410A replaced R-22 in many residential systems because it
contains no chlorine and therefore does not deplete the ozone layer.
7. What instrument is commonly used to verify system airflow?
, A. Vacuum pump
B. Refrigerant scale
C. Anemometer
D. Megohmmeter
Rationale: An anemometer measures air velocity, allowing technicians to
calculate airflow through ducts or equipment.
8. A dirty evaporator coil most likely causes:
A. High airflow
B. Reduced cooling capacity
C. Increased combustion efficiency
D. Lower head pressure
Rationale: Dirt restricts airflow and heat transfer, reducing evaporator
performance and overall cooling capacity.
9. The primary purpose of a filter-drier is to:
A. Raise refrigerant pressure
B. Remove moisture and contaminants
C. Increase superheat
D. Cool compressor oil
Rationale: Filter-driers trap debris and absorb moisture that could damage
system components or form acids.
Contractor Exam Practice Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. Which refrigerant property is most directly responsible for absorbing
heat in the evaporator?
A. High density
B. High viscosity
C. Latent heat of vaporization
D. Low molecular weight
Rationale: Refrigerants absorb large amounts of heat during the phase
change from liquid to vapor. This latent heat of vaporization is the primary
mechanism by which cooling occurs in the evaporator.
2. What is the primary purpose of the compressor in a vapor-
compression refrigeration system?
,A. Condense refrigerant
B. Remove moisture
C. Raise refrigerant pressure and circulate refrigerant
D. Meter refrigerant flow
Rationale: The compressor increases refrigerant pressure and temperature
while circulating refrigerant throughout the system, enabling the
refrigeration cycle to continue.
3. Which component meters refrigerant into the evaporator?
A. Compressor
B. Condenser
C. Expansion valve
D. Accumulator
Rationale: The expansion valve controls refrigerant flow into the
evaporator while reducing pressure, allowing the refrigerant to boil and
absorb heat.
4. Superheat is best defined as:
A. Heat removed by the condenser
B. Temperature above the refrigerant's saturation temperature
C. Difference between indoor and outdoor temperatures
D. Compressor discharge temperature
,Rationale: Superheat measures how much the refrigerant vapor
temperature exceeds its saturation temperature, ensuring only vapor
enters the compressor.
5. Subcooling refers to:
A. Cooling air below freezing
B. Heating refrigerant above saturation
C. Cooling liquid refrigerant below its saturation temperature
D. Reducing compressor temperature
Rationale: Subcooling ensures liquid refrigerant reaches the metering
device without flashing into vapor prematurely.
6. Which refrigerant has a low ozone depletion potential and is
commonly used in modern residential systems?
A. R-22
B. R-410A
C. R-12
D. R-11
Rationale: R-410A replaced R-22 in many residential systems because it
contains no chlorine and therefore does not deplete the ozone layer.
7. What instrument is commonly used to verify system airflow?
, A. Vacuum pump
B. Refrigerant scale
C. Anemometer
D. Megohmmeter
Rationale: An anemometer measures air velocity, allowing technicians to
calculate airflow through ducts or equipment.
8. A dirty evaporator coil most likely causes:
A. High airflow
B. Reduced cooling capacity
C. Increased combustion efficiency
D. Lower head pressure
Rationale: Dirt restricts airflow and heat transfer, reducing evaporator
performance and overall cooling capacity.
9. The primary purpose of a filter-drier is to:
A. Raise refrigerant pressure
B. Remove moisture and contaminants
C. Increase superheat
D. Cool compressor oil
Rationale: Filter-driers trap debris and absorb moisture that could damage
system components or form acids.
