Maryland HVACR Master Restricted
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 compressor discharge pressure
B. Remove moisture from the refrigerant
C. Regulate refrigerant flow into the evaporator
D. Increase condenser airflow
Rationale: The metering device controls the amount of liquid refrigerant
entering the evaporator and creates the pressure drop between the
high and low sides. Proper metering is essential for maintaining the
desired evaporator superheat and system performance.
Question 2
,Which component removes heat from the conditioned space in a
conventional air-conditioning system?
A. Condenser
B. Compressor
C. Expansion valve
D. Evaporator
Rationale: The evaporator absorbs heat from indoor air as refrigerant
changes from a low-pressure liquid-vapor mixture into vapor. The
condenser then rejects that absorbed heat to the outdoor environment.
Question 3
What condition is indicated by high suction pressure and low superheat
on a fixed-orifice air-conditioning system?
A. Undercharge
B. Possible overfeeding or overcharge
C. Restricted evaporator airflow
D. Severe condenser restriction
Rationale: High suction pressure combined with low superheat can
indicate that too much refrigerant is entering the evaporator.
Depending on operating conditions, an overcharge or excessive
refrigerant feed can produce this symptom.
,Question 4
What is the primary function of the compressor?
A. Convert vapor to liquid
B. Remove moisture from refrigerant
C. Raise refrigerant vapor pressure and circulate refrigerant
D. Meter liquid refrigerant
Rationale: The compressor draws low-pressure vapor from the
evaporator and compresses it into a higher-pressure, higher-
temperature vapor. It also provides the pressure differential needed to
circulate refrigerant through the system.
Question 5
Which instrument is commonly used to measure refrigerant pressure?
A. Manometer
B. Thermocouple
C. Psychrometer
D. Manifold gauge set
Rationale: A manifold gauge set provides access to the refrigeration
system's pressure sides and allows technicians to monitor suction and
discharge pressures. Digital gauges can also provide saturation-
temperature and diagnostic information.
, Question 6
What is superheat?
A. The temperature of liquid refrigerant below saturation
B. The temperature of a vapor above its saturation temperature
C. The temperature difference between indoor and outdoor air
D. The pressure difference between the suction and discharge lines
Rationale: Superheat is the amount by which a vapor's actual
temperature exceeds its saturation temperature at a given pressure.
Measuring superheat helps determine whether refrigerant is completely
vaporized before reaching the compressor.
Question 7
What does subcooling measure?
A. Vapor temperature above saturation
B. Compressor temperature rise
C. Liquid temperature below its saturation temperature
D. Evaporator temperature above room temperature
Rationale: Subcooling is the difference between the refrigerant's
saturation temperature at a given condensing pressure and the actual
liquid temperature. It is particularly useful for evaluating systems
equipped with thermostatic expansion valves.
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 compressor discharge pressure
B. Remove moisture from the refrigerant
C. Regulate refrigerant flow into the evaporator
D. Increase condenser airflow
Rationale: The metering device controls the amount of liquid refrigerant
entering the evaporator and creates the pressure drop between the
high and low sides. Proper metering is essential for maintaining the
desired evaporator superheat and system performance.
Question 2
,Which component removes heat from the conditioned space in a
conventional air-conditioning system?
A. Condenser
B. Compressor
C. Expansion valve
D. Evaporator
Rationale: The evaporator absorbs heat from indoor air as refrigerant
changes from a low-pressure liquid-vapor mixture into vapor. The
condenser then rejects that absorbed heat to the outdoor environment.
Question 3
What condition is indicated by high suction pressure and low superheat
on a fixed-orifice air-conditioning system?
A. Undercharge
B. Possible overfeeding or overcharge
C. Restricted evaporator airflow
D. Severe condenser restriction
Rationale: High suction pressure combined with low superheat can
indicate that too much refrigerant is entering the evaporator.
Depending on operating conditions, an overcharge or excessive
refrigerant feed can produce this symptom.
,Question 4
What is the primary function of the compressor?
A. Convert vapor to liquid
B. Remove moisture from refrigerant
C. Raise refrigerant vapor pressure and circulate refrigerant
D. Meter liquid refrigerant
Rationale: The compressor draws low-pressure vapor from the
evaporator and compresses it into a higher-pressure, higher-
temperature vapor. It also provides the pressure differential needed to
circulate refrigerant through the system.
Question 5
Which instrument is commonly used to measure refrigerant pressure?
A. Manometer
B. Thermocouple
C. Psychrometer
D. Manifold gauge set
Rationale: A manifold gauge set provides access to the refrigeration
system's pressure sides and allows technicians to monitor suction and
discharge pressures. Digital gauges can also provide saturation-
temperature and diagnostic information.
, Question 6
What is superheat?
A. The temperature of liquid refrigerant below saturation
B. The temperature of a vapor above its saturation temperature
C. The temperature difference between indoor and outdoor air
D. The pressure difference between the suction and discharge lines
Rationale: Superheat is the amount by which a vapor's actual
temperature exceeds its saturation temperature at a given pressure.
Measuring superheat helps determine whether refrigerant is completely
vaporized before reaching the compressor.
Question 7
What does subcooling measure?
A. Vapor temperature above saturation
B. Compressor temperature rise
C. Liquid temperature below its saturation temperature
D. Evaporator temperature above room temperature
Rationale: Subcooling is the difference between the refrigerant's
saturation temperature at a given condensing pressure and the actual
liquid temperature. It is particularly useful for evaluating systems
equipped with thermostatic expansion valves.
