Wisconsin HVAC Qualifier Examination
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A|
Instant Download Pdf
Question 1
What is the primary purpose of a refrigerant metering device in a
vapor-compression refrigeration system?
A. Increase refrigerant pressure before the compressor
B. Remove moisture from the refrigerant
C. Control the amount of refrigerant entering the evaporator
D. Increase refrigerant temperature entering the condenser
Answer: C. Control the amount of refrigerant entering the evaporator
Rationale: The metering device creates a pressure drop between the
high-pressure liquid side and the low-pressure evaporator side. It also
regulates refrigerant flow so the evaporator receives an appropriate
amount of refrigerant for the operating load.
,Question 2
Which component removes heat from the conditioned space in a
typical air-conditioning system?
A. Condenser
B. Evaporator
C. Compressor
D. Receiver
Answer: B. Evaporator
Rationale: The evaporator absorbs heat from indoor air as refrigerant
evaporates inside its tubing. The condenser performs the opposite
function by rejecting heat to the surrounding environment.
Question 3
What is the main function of the compressor in a refrigeration cycle?
A. Lower refrigerant pressure
B. Remove moisture from the air
C. Circulate refrigerant and raise its pressure and temperature
D. Convert liquid refrigerant directly into ice
,Answer: C. Circulate refrigerant and raise its pressure and
temperature
Rationale: The compressor draws low-pressure refrigerant vapor from
the evaporator and compresses it into a high-pressure, high-
temperature vapor. This allows the refrigerant to reject heat
effectively in the condenser.
Question 4
Which refrigerant condition should normally exist at the compressor
inlet?
A. High-pressure liquid
B. Low-pressure vapor
C. High-pressure liquid-vapor mixture
D. Low-pressure subcooled liquid
Answer: B. Low-pressure vapor
Rationale: A properly operating vapor-compression system supplies
vapor to the compressor. Liquid entering the compressor can cause
liquid slugging and potentially damage compressor components.
, Question 5
What does superheat describe in a refrigeration system?
A. The temperature of liquid below its saturation temperature
B. The temperature of vapor above its saturation temperature
C. The pressure difference between the condenser and evaporator
D. The temperature difference between indoor and outdoor air
Answer: B. The temperature of vapor above its saturation
temperature
Rationale: Superheat is the number of degrees a vapor's actual
temperature is above its saturation temperature at a given pressure.
Measuring superheat is useful for evaluating evaporator performance
and protecting the compressor from liquid refrigerant.
Question 6
What does subcooling indicate?
A. Liquid refrigerant is below its saturation temperature
B. Vapor refrigerant is above its saturation temperature
C. Refrigerant has reached compressor discharge temperature
D. Air has been cooled below its dew point
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A|
Instant Download Pdf
Question 1
What is the primary purpose of a refrigerant metering device in a
vapor-compression refrigeration system?
A. Increase refrigerant pressure before the compressor
B. Remove moisture from the refrigerant
C. Control the amount of refrigerant entering the evaporator
D. Increase refrigerant temperature entering the condenser
Answer: C. Control the amount of refrigerant entering the evaporator
Rationale: The metering device creates a pressure drop between the
high-pressure liquid side and the low-pressure evaporator side. It also
regulates refrigerant flow so the evaporator receives an appropriate
amount of refrigerant for the operating load.
,Question 2
Which component removes heat from the conditioned space in a
typical air-conditioning system?
A. Condenser
B. Evaporator
C. Compressor
D. Receiver
Answer: B. Evaporator
Rationale: The evaporator absorbs heat from indoor air as refrigerant
evaporates inside its tubing. The condenser performs the opposite
function by rejecting heat to the surrounding environment.
Question 3
What is the main function of the compressor in a refrigeration cycle?
A. Lower refrigerant pressure
B. Remove moisture from the air
C. Circulate refrigerant and raise its pressure and temperature
D. Convert liquid refrigerant directly into ice
,Answer: C. Circulate refrigerant and raise its pressure and
temperature
Rationale: The compressor draws low-pressure refrigerant vapor from
the evaporator and compresses it into a high-pressure, high-
temperature vapor. This allows the refrigerant to reject heat
effectively in the condenser.
Question 4
Which refrigerant condition should normally exist at the compressor
inlet?
A. High-pressure liquid
B. Low-pressure vapor
C. High-pressure liquid-vapor mixture
D. Low-pressure subcooled liquid
Answer: B. Low-pressure vapor
Rationale: A properly operating vapor-compression system supplies
vapor to the compressor. Liquid entering the compressor can cause
liquid slugging and potentially damage compressor components.
, Question 5
What does superheat describe in a refrigeration system?
A. The temperature of liquid below its saturation temperature
B. The temperature of vapor above its saturation temperature
C. The pressure difference between the condenser and evaporator
D. The temperature difference between indoor and outdoor air
Answer: B. The temperature of vapor above its saturation
temperature
Rationale: Superheat is the number of degrees a vapor's actual
temperature is above its saturation temperature at a given pressure.
Measuring superheat is useful for evaluating evaporator performance
and protecting the compressor from liquid refrigerant.
Question 6
What does subcooling indicate?
A. Liquid refrigerant is below its saturation temperature
B. Vapor refrigerant is above its saturation temperature
C. Refrigerant has reached compressor discharge temperature
D. Air has been cooled below its dew point
