HVAC CONTRACTOR EXAM
Practice Questions with Answers and Rationale
150 Original Multiple-Choice Questions — Study and Review Guide
Contents
Section 1: Refrigeration Cycle Fundamentals
Section 2: Refrigerants, Recovery & EPA Section 608
Section 3: Electrical Theory & Motors
Section 4: Heating Systems & Combustion
Section 5: Heat Pumps
Section 6: Airflow, Duct Design & Psychrometrics
Section 7: System Installation, Brazing & Evacuation
Section 8: Troubleshooting & Diagnostics
Section 9: Codes, Standards & Safety
Section 10: Business, Estimating & Contractor Practices
,Section 1: Refrigeration Cycle Fundamentals
1. In the basic vapor-compression refrigeration cycle, which component
raises the pressure and temperature of the refrigerant vapor?
A. Evaporator
B. Compressor
C. Condenser
D. Metering device
Answer: B
Rationale: The compressor takes low-pressure, low-temperature vapor
from the evaporator and compresses it, raising both pressure and
temperature so heat can be rejected in the condenser.
2. Where in the refrigeration cycle does the refrigerant absorb heat from
the conditioned space?
A. Condenser
B. Compressor
C. Evaporator
D. Liquid line
Answer: C
Rationale: The evaporator is the low-pressure, low-temperature heat
exchanger where liquid refrigerant boils and absorbs heat from the air or
fluid being cooled.
3. The primary function of the metering device is to:
A. Increase refrigerant pressure
B. Create a pressure drop and meter refrigerant flow into the evaporator
C. Remove moisture from the system
D. Store excess refrigerant
Answer: B
, Rationale: The metering device (TXV, fixed orifice, or capillary tube)
creates the pressure drop between the high and low sides and controls the
rate of refrigerant flow into the evaporator.
4. "Superheat" is defined as:
A. The temperature of saturated vapor
B. Sensible heat added to a vapor above its saturation temperature at a
given pressure
C. Heat removed from a liquid below its condensing temperature
D. The total heat content of the refrigerant
Answer: B
Rationale: Superheat is the number of degrees a vapor has been heated
above the saturation (boiling) temperature corresponding to its pressure,
ensuring no liquid returns to the compressor.
5. "Subcooling" is measured at which point in the system?
A. Compressor suction line
B. Condenser outlet / liquid line
C. Evaporator inlet
D. Suction accumulator
Answer: B
Rationale: Subcooling is measured at the condenser outlet or liquid line,
indicating how many degrees the liquid refrigerant has been cooled below
its saturation temperature at that pressure.
6. Latent heat is best described as heat that:
A. Changes the temperature of a substance without a change of state
B. Causes a change of state without a change in temperature
C. Is always lost to the atmosphere
D. Only applies to solids
Answer: B
, Rationale: Latent heat is the energy absorbed or released during a phase
change (boiling, condensing, melting, freezing) while the temperature
remains constant.
7. Sensible heat is heat that:
A. Causes a change in temperature that can be measured with a
thermometer
B. Causes a change of state
C. Cannot be measured
D. Only exists in vapor
Answer: A
Rationale: Sensible heat changes the temperature of a substance without
changing its state, and is therefore detectable with a standard
thermometer.
8. One ton of refrigeration is equal to:
A. 6,000 BTU/hr
B. 12,000 BTU/hr
C. 24,000 BTU/hr
D. 1,000 BTU/hr
Answer: B
Rationale: One ton of refrigeration equals 12,000 BTU per hour, derived
from the heat required to melt one ton of ice in 24 hours (288,000 BTU ÷
24).
9. A BTU is defined as the amount of heat required to:
A. Raise one pound of water one degree Fahrenheit
B. Raise one gallon of water ten degrees Fahrenheit
C. Melt one pound of ice
D. Boil one pound of water
Answer: A
Practice Questions with Answers and Rationale
150 Original Multiple-Choice Questions — Study and Review Guide
Contents
Section 1: Refrigeration Cycle Fundamentals
Section 2: Refrigerants, Recovery & EPA Section 608
Section 3: Electrical Theory & Motors
Section 4: Heating Systems & Combustion
Section 5: Heat Pumps
Section 6: Airflow, Duct Design & Psychrometrics
Section 7: System Installation, Brazing & Evacuation
Section 8: Troubleshooting & Diagnostics
Section 9: Codes, Standards & Safety
Section 10: Business, Estimating & Contractor Practices
,Section 1: Refrigeration Cycle Fundamentals
1. In the basic vapor-compression refrigeration cycle, which component
raises the pressure and temperature of the refrigerant vapor?
A. Evaporator
B. Compressor
C. Condenser
D. Metering device
Answer: B
Rationale: The compressor takes low-pressure, low-temperature vapor
from the evaporator and compresses it, raising both pressure and
temperature so heat can be rejected in the condenser.
2. Where in the refrigeration cycle does the refrigerant absorb heat from
the conditioned space?
A. Condenser
B. Compressor
C. Evaporator
D. Liquid line
Answer: C
Rationale: The evaporator is the low-pressure, low-temperature heat
exchanger where liquid refrigerant boils and absorbs heat from the air or
fluid being cooled.
3. The primary function of the metering device is to:
A. Increase refrigerant pressure
B. Create a pressure drop and meter refrigerant flow into the evaporator
C. Remove moisture from the system
D. Store excess refrigerant
Answer: B
, Rationale: The metering device (TXV, fixed orifice, or capillary tube)
creates the pressure drop between the high and low sides and controls the
rate of refrigerant flow into the evaporator.
4. "Superheat" is defined as:
A. The temperature of saturated vapor
B. Sensible heat added to a vapor above its saturation temperature at a
given pressure
C. Heat removed from a liquid below its condensing temperature
D. The total heat content of the refrigerant
Answer: B
Rationale: Superheat is the number of degrees a vapor has been heated
above the saturation (boiling) temperature corresponding to its pressure,
ensuring no liquid returns to the compressor.
5. "Subcooling" is measured at which point in the system?
A. Compressor suction line
B. Condenser outlet / liquid line
C. Evaporator inlet
D. Suction accumulator
Answer: B
Rationale: Subcooling is measured at the condenser outlet or liquid line,
indicating how many degrees the liquid refrigerant has been cooled below
its saturation temperature at that pressure.
6. Latent heat is best described as heat that:
A. Changes the temperature of a substance without a change of state
B. Causes a change of state without a change in temperature
C. Is always lost to the atmosphere
D. Only applies to solids
Answer: B
, Rationale: Latent heat is the energy absorbed or released during a phase
change (boiling, condensing, melting, freezing) while the temperature
remains constant.
7. Sensible heat is heat that:
A. Causes a change in temperature that can be measured with a
thermometer
B. Causes a change of state
C. Cannot be measured
D. Only exists in vapor
Answer: A
Rationale: Sensible heat changes the temperature of a substance without
changing its state, and is therefore detectable with a standard
thermometer.
8. One ton of refrigeration is equal to:
A. 6,000 BTU/hr
B. 12,000 BTU/hr
C. 24,000 BTU/hr
D. 1,000 BTU/hr
Answer: B
Rationale: One ton of refrigeration equals 12,000 BTU per hour, derived
from the heat required to melt one ton of ice in 24 hours (288,000 BTU ÷
24).
9. A BTU is defined as the amount of heat required to:
A. Raise one pound of water one degree Fahrenheit
B. Raise one gallon of water ten degrees Fahrenheit
C. Melt one pound of ice
D. Boil one pound of water
Answer: A
