AZ L-75 Refrigeration & Heating Exam
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?
a. To generate heat
b. To increase humidity
c. To remove heat from a designated space or substance
d. To increase air pressure
Rationale: Refrigeration is fundamentally the process of removing
heat from a space, product, or substance and rejecting that heat to
another location. The refrigeration cycle accomplishes this through
evaporation, compression, condensation, and expansion.
2. Which component of a vapor-compression refrigeration system
removes heat from the conditioned space?
,a. Compressor
b. Condenser
c. Expansion valve
d. Evaporator
Rationale: The evaporator absorbs heat from the refrigerated or
conditioned space as the refrigerant changes from a low-pressure
liquid-vapor mixture into a vapor. This heat absorption is the cooling
effect of the system.
3. What is the primary function of the compressor?
a. Reduce refrigerant temperature
b. Raise refrigerant vapor pressure and temperature
c. Convert vapor directly into liquid
d. Meter refrigerant into the condenser
Rationale: The compressor takes low-pressure refrigerant vapor from
the evaporator and compresses it into a high-pressure, high-
temperature vapor. This allows the refrigerant to reject heat in the
condenser.
4. Which component rejects heat from the refrigerant to the
surrounding environment?
,a. Evaporator
b. Accumulator
c. Condenser
d. Expansion device
Rationale: The condenser removes heat from the high-pressure
refrigerant vapor. As heat is rejected, the refrigerant condenses into a
high-pressure liquid.
5. What is the primary function of an expansion valve?
a. Increase refrigerant pressure
b. Increase compressor capacity
c. Reduce refrigerant pressure and meter flow to the evaporator
d. Remove moisture from the system
Rationale: The expansion device creates a pressure drop between the
high-pressure liquid side and the low-pressure evaporator side. It also
controls the amount of refrigerant entering the evaporator.
6. Which refrigerant condition normally exists at the compressor
inlet?
a. High-pressure liquid
b. High-pressure vapor
, c. Low-pressure vapor
d. Low-pressure liquid
Rationale: Refrigerant leaving the evaporator should normally be
vapor. The compressor inlet is therefore on the low-pressure vapor
side of the refrigeration system.
7. What does superheat represent?
a. The temperature of saturated liquid below its boiling point
b. The temperature of a vapor above its saturation temperature
c. The pressure of liquid above atmospheric pressure
d. The temperature difference between condenser and ambient air
Rationale: Superheat is the number of degrees a vapor's actual
temperature is above its saturation temperature at a given pressure.
It is commonly measured at the evaporator outlet or compressor inlet.
8. What does subcooling indicate?
a. Vapor temperature above saturation
b. Compressor discharge temperature
c. Liquid temperature below its saturation temperature
d. Evaporator temperature above room temperature
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A| Instant
Download Pdf
1. What is the primary purpose of a refrigeration system?
a. To generate heat
b. To increase humidity
c. To remove heat from a designated space or substance
d. To increase air pressure
Rationale: Refrigeration is fundamentally the process of removing
heat from a space, product, or substance and rejecting that heat to
another location. The refrigeration cycle accomplishes this through
evaporation, compression, condensation, and expansion.
2. Which component of a vapor-compression refrigeration system
removes heat from the conditioned space?
,a. Compressor
b. Condenser
c. Expansion valve
d. Evaporator
Rationale: The evaporator absorbs heat from the refrigerated or
conditioned space as the refrigerant changes from a low-pressure
liquid-vapor mixture into a vapor. This heat absorption is the cooling
effect of the system.
3. What is the primary function of the compressor?
a. Reduce refrigerant temperature
b. Raise refrigerant vapor pressure and temperature
c. Convert vapor directly into liquid
d. Meter refrigerant into the condenser
Rationale: The compressor takes low-pressure refrigerant vapor from
the evaporator and compresses it into a high-pressure, high-
temperature vapor. This allows the refrigerant to reject heat in the
condenser.
4. Which component rejects heat from the refrigerant to the
surrounding environment?
,a. Evaporator
b. Accumulator
c. Condenser
d. Expansion device
Rationale: The condenser removes heat from the high-pressure
refrigerant vapor. As heat is rejected, the refrigerant condenses into a
high-pressure liquid.
5. What is the primary function of an expansion valve?
a. Increase refrigerant pressure
b. Increase compressor capacity
c. Reduce refrigerant pressure and meter flow to the evaporator
d. Remove moisture from the system
Rationale: The expansion device creates a pressure drop between the
high-pressure liquid side and the low-pressure evaporator side. It also
controls the amount of refrigerant entering the evaporator.
6. Which refrigerant condition normally exists at the compressor
inlet?
a. High-pressure liquid
b. High-pressure vapor
, c. Low-pressure vapor
d. Low-pressure liquid
Rationale: Refrigerant leaving the evaporator should normally be
vapor. The compressor inlet is therefore on the low-pressure vapor
side of the refrigeration system.
7. What does superheat represent?
a. The temperature of saturated liquid below its boiling point
b. The temperature of a vapor above its saturation temperature
c. The pressure of liquid above atmospheric pressure
d. The temperature difference between condenser and ambient air
Rationale: Superheat is the number of degrees a vapor's actual
temperature is above its saturation temperature at a given pressure.
It is commonly measured at the evaporator outlet or compressor inlet.
8. What does subcooling indicate?
a. Vapor temperature above saturation
b. Compressor discharge temperature
c. Liquid temperature below its saturation temperature
d. Evaporator temperature above room temperature
