Star Hvac Mastery Exam - 2026/2027 Update | Complete
Questions with Correct Detailed Answers | 100% Guaranteed
Pass Brand New Version!!!
Question 1
What is the primary purpose of an HVAC system?
A. To generate electrical power
B. To control indoor temperature, humidity, air quality, and air movement
C. To provide plumbing services
D. To eliminate all outdoor air
Correct Answer: B. To control indoor temperature, humidity, air quality,
and air movement
Rationale: HVAC stands for heating, ventilation, and air conditioning. A
complete HVAC system is designed to maintain acceptable indoor
environmental conditions by controlling temperature, humidity, ventilation,
air circulation, and, depending on the system, filtration and air quality.
Heating and cooling capacity alone do not fully describe HVAC performance
because proper ventilation and humidity control are also important.
Question 2
Which component is responsible for transferring heat from indoor air to the
refrigerant in a typical air-conditioning system?
A. Condenser
B. Compressor
C. Evaporator
D. Receiver
Correct Answer: C. Evaporator
Rationale: The evaporator absorbs heat from the indoor air. Refrigerant
enters the evaporator at a low pressure and temperature and absorbs heat as
it evaporates. The blower moves indoor air across the evaporator coil,
1
,allowing heat to transfer from the air into the refrigerant. The condenser
performs the opposite heat-transfer function by rejecting heat to the
surrounding environment.
Question 3
What is the primary function of the compressor in a vapor-compression
refrigeration system?
A. Remove moisture from indoor air
B. Raise the pressure and temperature of the refrigerant vapor
C. Reduce refrigerant pressure
D. Filter the refrigerant
Correct Answer: B. Raise the pressure and temperature of the
refrigerant vapor
Rationale: The compressor receives relatively low-pressure refrigerant vapor
from the evaporator and compresses it into a high-pressure, high-
temperature vapor. This pressure increase allows the refrigerant to reject
heat in the condenser. The compressor is therefore a central component of the
refrigeration cycle and must be properly lubricated and supplied with suitable
refrigerant vapor.
Question 4
What happens to refrigerant pressure as it passes through a typical metering
device?
A. It increases significantly
B. It remains exactly the same
C. It decreases significantly
D. It becomes atmospheric pressure
Correct Answer: C. It decreases significantly
2
,Rationale: The metering device creates a pressure drop between the high-
pressure liquid side and the low-pressure evaporator side. This pressure
reduction causes part of the refrigerant to flash into vapor and lowers the
refrigerant's saturation temperature, allowing it to absorb heat effectively in
the evaporator.
Question 5
Which component rejects heat from the refrigerant to the surrounding
environment?
A. Evaporator
B. Condenser
C. Expansion valve
D. Accumulator
Correct Answer: B. Condenser
Rationale: The condenser receives high-pressure, high-temperature
refrigerant vapor from the compressor. As air or water removes heat from the
refrigerant, the vapor condenses into a high-pressure liquid. The heat rejected
includes both the heat absorbed inside the conditioned space and the
compressor's added heat of compression.
Question 6
What is superheat?
A. The temperature of a liquid below its freezing point
B. The temperature of a vapor above its saturation temperature at a given
pressure
C. The pressure difference across a compressor
D. The temperature difference between outdoor and indoor air
Correct Answer: B. The temperature of a vapor above its saturation
temperature at a given pressure
3
, Rationale: Superheat is the amount by which a vapor's actual temperature
exceeds its saturation temperature at the measured pressure. In HVAC
diagnostics, evaporator outlet superheat can help determine whether the
evaporator is receiving an appropriate amount of refrigerant. Excessive or
insufficient superheat can indicate different system conditions, so
measurements must be interpreted in context.
Question 7
What is subcooling?
A. Cooling a vapor below its saturation temperature
B. Cooling a liquid below its saturation temperature at a given pressure
C. Reducing compressor speed
D. Removing air from a duct system
Correct Answer: B. Cooling a liquid below its saturation temperature at a
given pressure
Rationale: Subcooling occurs when liquid refrigerant is cooled below its
saturation temperature at the corresponding pressure. Condenser outlet
subcooling is commonly measured during system diagnosis and can provide
useful information about refrigerant charge and condenser performance. The
correct interpretation depends on the system design and manufacturer's
specifications.
Question 8
Which instrument is commonly used to measure refrigerant pressure?
A. Manifold gauge set
B. Megohmmeter only
C. Psychrometer only
D. Clamp meter only
Correct Answer: A. Manifold gauge set
4
Questions with Correct Detailed Answers | 100% Guaranteed
Pass Brand New Version!!!
Question 1
What is the primary purpose of an HVAC system?
A. To generate electrical power
B. To control indoor temperature, humidity, air quality, and air movement
C. To provide plumbing services
D. To eliminate all outdoor air
Correct Answer: B. To control indoor temperature, humidity, air quality,
and air movement
Rationale: HVAC stands for heating, ventilation, and air conditioning. A
complete HVAC system is designed to maintain acceptable indoor
environmental conditions by controlling temperature, humidity, ventilation,
air circulation, and, depending on the system, filtration and air quality.
Heating and cooling capacity alone do not fully describe HVAC performance
because proper ventilation and humidity control are also important.
Question 2
Which component is responsible for transferring heat from indoor air to the
refrigerant in a typical air-conditioning system?
A. Condenser
B. Compressor
C. Evaporator
D. Receiver
Correct Answer: C. Evaporator
Rationale: The evaporator absorbs heat from the indoor air. Refrigerant
enters the evaporator at a low pressure and temperature and absorbs heat as
it evaporates. The blower moves indoor air across the evaporator coil,
1
,allowing heat to transfer from the air into the refrigerant. The condenser
performs the opposite heat-transfer function by rejecting heat to the
surrounding environment.
Question 3
What is the primary function of the compressor in a vapor-compression
refrigeration system?
A. Remove moisture from indoor air
B. Raise the pressure and temperature of the refrigerant vapor
C. Reduce refrigerant pressure
D. Filter the refrigerant
Correct Answer: B. Raise the pressure and temperature of the
refrigerant vapor
Rationale: The compressor receives relatively low-pressure refrigerant vapor
from the evaporator and compresses it into a high-pressure, high-
temperature vapor. This pressure increase allows the refrigerant to reject
heat in the condenser. The compressor is therefore a central component of the
refrigeration cycle and must be properly lubricated and supplied with suitable
refrigerant vapor.
Question 4
What happens to refrigerant pressure as it passes through a typical metering
device?
A. It increases significantly
B. It remains exactly the same
C. It decreases significantly
D. It becomes atmospheric pressure
Correct Answer: C. It decreases significantly
2
,Rationale: The metering device creates a pressure drop between the high-
pressure liquid side and the low-pressure evaporator side. This pressure
reduction causes part of the refrigerant to flash into vapor and lowers the
refrigerant's saturation temperature, allowing it to absorb heat effectively in
the evaporator.
Question 5
Which component rejects heat from the refrigerant to the surrounding
environment?
A. Evaporator
B. Condenser
C. Expansion valve
D. Accumulator
Correct Answer: B. Condenser
Rationale: The condenser receives high-pressure, high-temperature
refrigerant vapor from the compressor. As air or water removes heat from the
refrigerant, the vapor condenses into a high-pressure liquid. The heat rejected
includes both the heat absorbed inside the conditioned space and the
compressor's added heat of compression.
Question 6
What is superheat?
A. The temperature of a liquid below its freezing point
B. The temperature of a vapor above its saturation temperature at a given
pressure
C. The pressure difference across a compressor
D. The temperature difference between outdoor and indoor air
Correct Answer: B. The temperature of a vapor above its saturation
temperature at a given pressure
3
, Rationale: Superheat is the amount by which a vapor's actual temperature
exceeds its saturation temperature at the measured pressure. In HVAC
diagnostics, evaporator outlet superheat can help determine whether the
evaporator is receiving an appropriate amount of refrigerant. Excessive or
insufficient superheat can indicate different system conditions, so
measurements must be interpreted in context.
Question 7
What is subcooling?
A. Cooling a vapor below its saturation temperature
B. Cooling a liquid below its saturation temperature at a given pressure
C. Reducing compressor speed
D. Removing air from a duct system
Correct Answer: B. Cooling a liquid below its saturation temperature at a
given pressure
Rationale: Subcooling occurs when liquid refrigerant is cooled below its
saturation temperature at the corresponding pressure. Condenser outlet
subcooling is commonly measured during system diagnosis and can provide
useful information about refrigerant charge and condenser performance. The
correct interpretation depends on the system design and manufacturer's
specifications.
Question 8
Which instrument is commonly used to measure refrigerant pressure?
A. Manifold gauge set
B. Megohmmeter only
C. Psychrometer only
D. Clamp meter only
Correct Answer: A. Manifold gauge set
4
