Master HVAC Technician Exam Practice
Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1.A commercial HVAC system uses a vapor-compression refrigeration cycle.
During normal operation, the compressor raises the pressure and
temperature of the refrigerant vapor before it enters the condenser. Which
process occurs inside the condenser that allows the refrigerant to reject
heat and become a liquid?
A. The refrigerant absorbs latent heat from the evaporator coil
B. The refrigerant undergoes a pressure drop and rapid expansion
C. The refrigerant releases sensible and latent heat to the surrounding
environment
D. The refrigerant increases in superheat before entering the metering
device
Correct Answer: C
The condenser removes heat from the high-pressure refrigerant vapor by
rejecting both sensible heat and latent heat, causing the vapor to condense
into a high-pressure liquid before moving to the expansion device.
2. A master HVAC technician is diagnosing a split-system air conditioner
with poor cooling performance. Measurements show low suction
pressure, high superheat, and a cold evaporator coil. What is the most
likely cause?
,A. Excessive refrigerant charge
B. Restricted refrigerant flow into the evaporator
C. Dirty condenser coil causing high head pressure
D. Overfeeding TXV causing liquid refrigerant return
Correct Answer: B
A restricted metering device or refrigerant restriction reduces refrigerant
entering the evaporator, causing low suction pressure, high superheat, and
inadequate cooling capacity.
3. A technician measures refrigerant superheat at the evaporator outlet.
What does superheat indicate?
A. The temperature difference between liquid refrigerant and saturated
liquid temperature
B. The temperature increase of refrigerant vapor above its boiling
temperature at a given pressure
C. The pressure difference between suction and discharge sides
D. The amount of refrigerant dissolved in compressor oil
Correct Answer: B
Superheat measures how much warmer refrigerant vapor is compared
with its saturation temperature at the measured pressure, ensuring only
vapor enters the compressor.
4. In a refrigeration system using a thermostatic expansion valve (TXV),
the primary function of the TXV is to:
A. Maintain constant condenser pressure
B. Regulate refrigerant flow into the evaporator based on superheat
C. Increase compressor discharge temperature
D. Remove moisture from the refrigerant circuit
Correct Answer: B
,A TXV modulates refrigerant flow into the evaporator to maintain proper
superheat and maximize evaporator efficiency while preventing liquid
refrigerant from reaching the compressor.
5. A rooftop HVAC unit has a compressor that repeatedly cycles on and
off due to high-pressure trips. Which condition is most likely
responsible?
A. Low evaporator airflow
B. Dirty condenser coil or restricted condenser airflow
C. Low refrigerant charge
D. Oversized evaporator coil
Correct Answer: B
High-pressure trips commonly occur when condenser heat rejection is
reduced by dirty coils, blocked airflow, or condenser fan problems, causing
excessive head pressure.
6. A technician is selecting ductwork for a large commercial air
distribution system. Which factor has the greatest effect on duct static
pressure losses?
A. Duct color and insulation type only
B. Air velocity, duct size, fittings, and surface resistance
C. Refrigerant type used in the system
D. Compressor horsepower rating
Correct Answer: B
Duct pressure losses depend primarily on airflow velocity, duct dimensions,
friction, and resistance created by fittings such as elbows and transitions.
7. The purpose of a psychrometric chart in HVAC design and
troubleshooting is to analyze:
, A. Electrical resistance values
B. Refrigerant pressure relationships only
C. Air properties including temperature, humidity, and enthalpy
D. Compressor mechanical tolerances
Correct Answer: C
Psychrometric charts allow HVAC professionals to evaluate air conditions
such as dry-bulb temperature, wet-bulb temperature, humidity ratio, and
enthalpy during system operation.
8. A furnace heat exchanger develops a crack. Why is this considered a
serious safety concern?
A. It reduces refrigerant superheat
B. It can allow combustion gases such as carbon monoxide into occupied
spaces
C. It increases evaporator airflow
D. It causes excessive condenser subcooling
Correct Answer: B
A cracked heat exchanger can leak carbon monoxide and other combustion
products into the building air supply, creating a hazardous indoor air
quality condition.
9. In an air-conditioning system, subcooling is used primarily to
determine:
A. Whether the liquid refrigerant leaving the condenser contains excessive
vapor
B. Whether compressor bearings are worn
C. Whether indoor humidity is too low
D. Whether the evaporator fan motor is oversized
Correct Answer: A
Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1.A commercial HVAC system uses a vapor-compression refrigeration cycle.
During normal operation, the compressor raises the pressure and
temperature of the refrigerant vapor before it enters the condenser. Which
process occurs inside the condenser that allows the refrigerant to reject
heat and become a liquid?
A. The refrigerant absorbs latent heat from the evaporator coil
B. The refrigerant undergoes a pressure drop and rapid expansion
C. The refrigerant releases sensible and latent heat to the surrounding
environment
D. The refrigerant increases in superheat before entering the metering
device
Correct Answer: C
The condenser removes heat from the high-pressure refrigerant vapor by
rejecting both sensible heat and latent heat, causing the vapor to condense
into a high-pressure liquid before moving to the expansion device.
2. A master HVAC technician is diagnosing a split-system air conditioner
with poor cooling performance. Measurements show low suction
pressure, high superheat, and a cold evaporator coil. What is the most
likely cause?
,A. Excessive refrigerant charge
B. Restricted refrigerant flow into the evaporator
C. Dirty condenser coil causing high head pressure
D. Overfeeding TXV causing liquid refrigerant return
Correct Answer: B
A restricted metering device or refrigerant restriction reduces refrigerant
entering the evaporator, causing low suction pressure, high superheat, and
inadequate cooling capacity.
3. A technician measures refrigerant superheat at the evaporator outlet.
What does superheat indicate?
A. The temperature difference between liquid refrigerant and saturated
liquid temperature
B. The temperature increase of refrigerant vapor above its boiling
temperature at a given pressure
C. The pressure difference between suction and discharge sides
D. The amount of refrigerant dissolved in compressor oil
Correct Answer: B
Superheat measures how much warmer refrigerant vapor is compared
with its saturation temperature at the measured pressure, ensuring only
vapor enters the compressor.
4. In a refrigeration system using a thermostatic expansion valve (TXV),
the primary function of the TXV is to:
A. Maintain constant condenser pressure
B. Regulate refrigerant flow into the evaporator based on superheat
C. Increase compressor discharge temperature
D. Remove moisture from the refrigerant circuit
Correct Answer: B
,A TXV modulates refrigerant flow into the evaporator to maintain proper
superheat and maximize evaporator efficiency while preventing liquid
refrigerant from reaching the compressor.
5. A rooftop HVAC unit has a compressor that repeatedly cycles on and
off due to high-pressure trips. Which condition is most likely
responsible?
A. Low evaporator airflow
B. Dirty condenser coil or restricted condenser airflow
C. Low refrigerant charge
D. Oversized evaporator coil
Correct Answer: B
High-pressure trips commonly occur when condenser heat rejection is
reduced by dirty coils, blocked airflow, or condenser fan problems, causing
excessive head pressure.
6. A technician is selecting ductwork for a large commercial air
distribution system. Which factor has the greatest effect on duct static
pressure losses?
A. Duct color and insulation type only
B. Air velocity, duct size, fittings, and surface resistance
C. Refrigerant type used in the system
D. Compressor horsepower rating
Correct Answer: B
Duct pressure losses depend primarily on airflow velocity, duct dimensions,
friction, and resistance created by fittings such as elbows and transitions.
7. The purpose of a psychrometric chart in HVAC design and
troubleshooting is to analyze:
, A. Electrical resistance values
B. Refrigerant pressure relationships only
C. Air properties including temperature, humidity, and enthalpy
D. Compressor mechanical tolerances
Correct Answer: C
Psychrometric charts allow HVAC professionals to evaluate air conditions
such as dry-bulb temperature, wet-bulb temperature, humidity ratio, and
enthalpy during system operation.
8. A furnace heat exchanger develops a crack. Why is this considered a
serious safety concern?
A. It reduces refrigerant superheat
B. It can allow combustion gases such as carbon monoxide into occupied
spaces
C. It increases evaporator airflow
D. It causes excessive condenser subcooling
Correct Answer: B
A cracked heat exchanger can leak carbon monoxide and other combustion
products into the building air supply, creating a hazardous indoor air
quality condition.
9. In an air-conditioning system, subcooling is used primarily to
determine:
A. Whether the liquid refrigerant leaving the condenser contains excessive
vapor
B. Whether compressor bearings are worn
C. Whether indoor humidity is too low
D. Whether the evaporator fan motor is oversized
Correct Answer: A
