NATE Core Service Certification
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A Instant Download Pdf
1. What is the primary purpose of a thermostat in an HVAC system?
A. To increase refrigerant pressure
B. To circulate refrigerant
C. To sense and control space temperature
D. To filter return air
Answer: To sense and control space temperature
Rationale: A thermostat monitors space temperature and signals the HVAC
equipment to provide heating or cooling as needed.
2. Which component is responsible for moving air through a forced-air HVAC
system?
A. Compressor
B. Blower
C. Condenser
D. Expansion valve
Answer: Blower
Rationale: The blower moves conditioned air through the duct system and
across the heat exchanger or evaporator coil.
, 3. What is the main function of a compressor in a vapor-compression
refrigeration system?
A. Lower refrigerant temperature
B. Increase refrigerant pressure and circulate refrigerant
C. Remove moisture from indoor air
D. Meter refrigerant into the condenser
Answer: Increase refrigerant pressure and circulate refrigerant
Rationale: The compressor raises the pressure and temperature of refrigerant
vapor and drives refrigerant through the system.
4. Which component rejects heat from the refrigerant to the surrounding
environment during cooling operation?
A. Evaporator
B. Condenser
C. Accumulator
D. Metering device
Answer: Condenser
Rationale: The condenser removes heat from the high-pressure refrigerant
vapor, causing it to condense into a liquid.
5. Where does refrigerant normally absorb heat from the conditioned space?
A. Compressor
B. Condenser
C. Evaporator
D. Receiver
Answer: Evaporator
Rationale: The evaporator absorbs heat from indoor air or another load as the
refrigerant evaporates.
6. What is sensible heat?
A. Heat associated with a change in moisture content
, B. Heat that causes a change in temperature
C. Heat contained only in refrigerant
D. Heat that cannot be measured
Answer: Heat that causes a change in temperature
Rationale: Sensible heat changes temperature without changing the substance's
physical state or moisture content.
7. What is latent heat primarily associated with?
A. Temperature change
B. Voltage change
C. Moisture or phase change
D. Air velocity
Answer: Moisture or phase change
Rationale: Latent heat is energy associated with a change of state or moisture
content without necessarily changing temperature.
8. What does relative humidity indicate?
A. The total amount of air in a room
B. The percentage of moisture in air relative to the maximum moisture it
can hold at a given temperature
C. The dry-bulb temperature
D. The air pressure inside a duct
Answer: The percentage of moisture in air relative to the maximum moisture it
can hold at a given temperature
Rationale: Relative humidity compares actual water vapor content with the
saturation capacity of air at that temperature.
9. Which instrument is commonly used to measure dry-bulb temperature?
A. Thermometer
B. Manometer
, C. Ammeter
D. Micron gauge
Answer: Thermometer
Rationale: A thermometer measures temperature directly and is commonly used
for dry-bulb temperature measurements.
10.What does a psychrometer measure or help determine?
A. Electrical resistance only
B. Air temperature and humidity conditions
C. Refrigerant pressure only
D. Compressor amperage
Answer: Air temperature and humidity conditions
Rationale: Psychrometric instruments use temperature measurements to
determine humidity-related properties of air.
11.What is the purpose of insulation on refrigerant suction lines?
A. To increase heat gain
B. To reduce unwanted heat transfer and condensation
C. To increase refrigerant pressure
D. To reduce compressor speed
Answer: To reduce unwanted heat transfer and condensation
Rationale: Suction-line insulation helps prevent heat gain into the refrigerant
and reduces condensation on the line.
12.Which type of heat transfer occurs through direct contact between
molecules?
A. Radiation
B. Convection
C. Conduction
D. Evaporation
Answer: Conduction
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A Instant Download Pdf
1. What is the primary purpose of a thermostat in an HVAC system?
A. To increase refrigerant pressure
B. To circulate refrigerant
C. To sense and control space temperature
D. To filter return air
Answer: To sense and control space temperature
Rationale: A thermostat monitors space temperature and signals the HVAC
equipment to provide heating or cooling as needed.
2. Which component is responsible for moving air through a forced-air HVAC
system?
A. Compressor
B. Blower
C. Condenser
D. Expansion valve
Answer: Blower
Rationale: The blower moves conditioned air through the duct system and
across the heat exchanger or evaporator coil.
, 3. What is the main function of a compressor in a vapor-compression
refrigeration system?
A. Lower refrigerant temperature
B. Increase refrigerant pressure and circulate refrigerant
C. Remove moisture from indoor air
D. Meter refrigerant into the condenser
Answer: Increase refrigerant pressure and circulate refrigerant
Rationale: The compressor raises the pressure and temperature of refrigerant
vapor and drives refrigerant through the system.
4. Which component rejects heat from the refrigerant to the surrounding
environment during cooling operation?
A. Evaporator
B. Condenser
C. Accumulator
D. Metering device
Answer: Condenser
Rationale: The condenser removes heat from the high-pressure refrigerant
vapor, causing it to condense into a liquid.
5. Where does refrigerant normally absorb heat from the conditioned space?
A. Compressor
B. Condenser
C. Evaporator
D. Receiver
Answer: Evaporator
Rationale: The evaporator absorbs heat from indoor air or another load as the
refrigerant evaporates.
6. What is sensible heat?
A. Heat associated with a change in moisture content
, B. Heat that causes a change in temperature
C. Heat contained only in refrigerant
D. Heat that cannot be measured
Answer: Heat that causes a change in temperature
Rationale: Sensible heat changes temperature without changing the substance's
physical state or moisture content.
7. What is latent heat primarily associated with?
A. Temperature change
B. Voltage change
C. Moisture or phase change
D. Air velocity
Answer: Moisture or phase change
Rationale: Latent heat is energy associated with a change of state or moisture
content without necessarily changing temperature.
8. What does relative humidity indicate?
A. The total amount of air in a room
B. The percentage of moisture in air relative to the maximum moisture it
can hold at a given temperature
C. The dry-bulb temperature
D. The air pressure inside a duct
Answer: The percentage of moisture in air relative to the maximum moisture it
can hold at a given temperature
Rationale: Relative humidity compares actual water vapor content with the
saturation capacity of air at that temperature.
9. Which instrument is commonly used to measure dry-bulb temperature?
A. Thermometer
B. Manometer
, C. Ammeter
D. Micron gauge
Answer: Thermometer
Rationale: A thermometer measures temperature directly and is commonly used
for dry-bulb temperature measurements.
10.What does a psychrometer measure or help determine?
A. Electrical resistance only
B. Air temperature and humidity conditions
C. Refrigerant pressure only
D. Compressor amperage
Answer: Air temperature and humidity conditions
Rationale: Psychrometric instruments use temperature measurements to
determine humidity-related properties of air.
11.What is the purpose of insulation on refrigerant suction lines?
A. To increase heat gain
B. To reduce unwanted heat transfer and condensation
C. To increase refrigerant pressure
D. To reduce compressor speed
Answer: To reduce unwanted heat transfer and condensation
Rationale: Suction-line insulation helps prevent heat gain into the refrigerant
and reduces condensation on the line.
12.Which type of heat transfer occurs through direct contact between
molecules?
A. Radiation
B. Convection
C. Conduction
D. Evaporation
Answer: Conduction
