Maryland HVACR Master Examination
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A| Instant
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1. What is the primary purpose of a refrigeration system's
evaporator?
A. Reject heat to the outdoor environment
B. Increase refrigerant pressure
C. Absorb heat from the conditioned space or product
D. Store liquid refrigerant
Rationale: The evaporator is the low-pressure heat-absorbing
component of the refrigeration cycle. Refrigerant enters the evaporator
at a low temperature and pressure and absorbs heat from the air,
water, or product being cooled.
2. Which component raises the pressure and temperature of
refrigerant vapor leaving the evaporator?
,A. Condenser
B. Expansion valve
C. Receiver
D. Compressor
Rationale: The compressor takes low-pressure, low-temperature vapor
from the evaporator and compresses it into a high-pressure, high-
temperature vapor. This prepares the refrigerant for heat rejection in
the condenser.
3. What is the primary function of a condenser?
A. Meter refrigerant into the evaporator
B. Reject heat from the refrigerant
C. Reduce compressor discharge pressure
D. Increase evaporator superheat
Rationale: The condenser removes heat from the hot refrigerant vapor.
As heat is rejected, the refrigerant condenses from a vapor into a liquid.
4. Which device controls the amount of refrigerant entering an
evaporator in many modern HVACR systems?
A. Accumulator
B. Receiver
,C. Thermostatic expansion valve
D. Liquid-line filter
Rationale: A thermostatic expansion valve, or TXV, meters refrigerant
flow into the evaporator according to evaporator load and superheat
conditions. Proper metering helps maintain efficient evaporator
operation and protects the compressor from liquid refrigerant.
5. What does evaporator superheat represent?
A. The temperature difference between liquid and vapor in the
condenser
B. The temperature of vapor above its saturation temperature
C. The pressure difference between suction and discharge
D. The temperature of liquid below its saturation temperature
Rationale: Superheat is the amount by which a vapor's actual
temperature exceeds its saturation temperature at a given pressure.
Measuring suction-line superheat is an important diagnostic technique
for evaluating refrigerant feeding and evaporator performance.
6. What condition exists when a liquid refrigerant is cooled below its
saturation temperature?
A. Superheat
B. Compression
, C. Subcooling
D. Flash gas
Rationale: Subcooling occurs when liquid refrigerant is below its
saturation temperature at the corresponding pressure. Adequate liquid-
line subcooling helps ensure that solid liquid refrigerant reaches the
metering device.
7. A compressor receives liquid refrigerant instead of vapor. What
condition can result?
A. Improved compressor lubrication
B. Increased condenser efficiency
C. Liquid slugging and compressor damage
D. Reduced electrical current
Rationale: Compressors are designed primarily to compress vapor.
Liquid refrigerant is essentially incompressible and can cause
mechanical damage, valve damage, bearing problems, or other serious
compressor failures.
8. Which component is normally installed in the liquid line to
remove moisture and contaminants?
A. Suction accumulator
B. Filter-drier
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A| Instant
Download Pdf
1. What is the primary purpose of a refrigeration system's
evaporator?
A. Reject heat to the outdoor environment
B. Increase refrigerant pressure
C. Absorb heat from the conditioned space or product
D. Store liquid refrigerant
Rationale: The evaporator is the low-pressure heat-absorbing
component of the refrigeration cycle. Refrigerant enters the evaporator
at a low temperature and pressure and absorbs heat from the air,
water, or product being cooled.
2. Which component raises the pressure and temperature of
refrigerant vapor leaving the evaporator?
,A. Condenser
B. Expansion valve
C. Receiver
D. Compressor
Rationale: The compressor takes low-pressure, low-temperature vapor
from the evaporator and compresses it into a high-pressure, high-
temperature vapor. This prepares the refrigerant for heat rejection in
the condenser.
3. What is the primary function of a condenser?
A. Meter refrigerant into the evaporator
B. Reject heat from the refrigerant
C. Reduce compressor discharge pressure
D. Increase evaporator superheat
Rationale: The condenser removes heat from the hot refrigerant vapor.
As heat is rejected, the refrigerant condenses from a vapor into a liquid.
4. Which device controls the amount of refrigerant entering an
evaporator in many modern HVACR systems?
A. Accumulator
B. Receiver
,C. Thermostatic expansion valve
D. Liquid-line filter
Rationale: A thermostatic expansion valve, or TXV, meters refrigerant
flow into the evaporator according to evaporator load and superheat
conditions. Proper metering helps maintain efficient evaporator
operation and protects the compressor from liquid refrigerant.
5. What does evaporator superheat represent?
A. The temperature difference between liquid and vapor in the
condenser
B. The temperature of vapor above its saturation temperature
C. The pressure difference between suction and discharge
D. The temperature of liquid below its saturation temperature
Rationale: Superheat is the amount by which a vapor's actual
temperature exceeds its saturation temperature at a given pressure.
Measuring suction-line superheat is an important diagnostic technique
for evaluating refrigerant feeding and evaporator performance.
6. What condition exists when a liquid refrigerant is cooled below its
saturation temperature?
A. Superheat
B. Compression
, C. Subcooling
D. Flash gas
Rationale: Subcooling occurs when liquid refrigerant is below its
saturation temperature at the corresponding pressure. Adequate liquid-
line subcooling helps ensure that solid liquid refrigerant reaches the
metering device.
7. A compressor receives liquid refrigerant instead of vapor. What
condition can result?
A. Improved compressor lubrication
B. Increased condenser efficiency
C. Liquid slugging and compressor damage
D. Reduced electrical current
Rationale: Compressors are designed primarily to compress vapor.
Liquid refrigerant is essentially incompressible and can cause
mechanical damage, valve damage, bearing problems, or other serious
compressor failures.
8. Which component is normally installed in the liquid line to
remove moisture and contaminants?
A. Suction accumulator
B. Filter-drier
