NEVADA (NV) C-21B AIR CONDITIONING CONTRACTOR PRACTICE
EXAM — VERSION 2 | NEVADA (NV) C-21B AIR CONDITIONING
CONTRACTOR PRACTICE EXAM VERSION 2 — 210 QUESTIONS AND
ANSWERS WITH DETAILED EXPLANATIONS | COMPREHENSIVE HVAC
CONTRACTOR TEST PREPARATION | 2026/2027 UPDATE
1. A properly sized suction line is important primarily because it helps
maintain adequate refrigerant flow and:
A. Prevents all compressor noise
B. Maintains acceptable pressure drop and oil return
C. Eliminates the need for insulation
D. Increases thermostat voltage
Answer: B
Explanation: Proper suction-line sizing helps control pressure loss and
supports reliable refrigerant and oil movement.
2. Which component normally rejects heat absorbed by the refrigerant
from the conditioned space?
A. Evaporator
B. Expansion device
C. Condenser
D. Accumulator
,Answer: C
Explanation: The condenser rejects the heat absorbed in the
evaporator plus the heat added by compressor operation.
3. What is the primary purpose of a thermostat in an HVAC system?
A. Compress refrigerant
B. Sense space temperature and control operation
C. Remove moisture from refrigerant
D. Increase duct pressure
Answer: B
Explanation: A thermostat senses temperature and sends control
signals to operate heating or cooling equipment.
4. Which condition generally increases the cooling load of a building?
A. Improved insulation
B. Reduced solar exposure
C. Increased occupancy
D. Reduced lighting
Answer: C
Explanation: Occupants generate both sensible and latent heat,
increasing the cooling requirement.
5. What is the principal purpose of a filter-drier?
,A. Increase refrigerant pressure
B. Remove moisture and contaminants
C. Increase airflow
D. Control room temperature
Answer: B
Explanation: Filter-driers protect refrigeration components by removing
moisture, acids, and contaminants.
6. A dirty air filter will most commonly cause:
A. Increased airflow
B. Reduced airflow
C. Increased refrigerant charge
D. Increased duct size
Answer: B
Explanation: A dirty filter creates additional resistance to airflow.
7. What is superheat?
A. Liquid refrigerant below saturation temperature
B. Vapor refrigerant above its saturation temperature
C. Air above room temperature
D. Refrigerant pressure above design pressure
Answer: B
Explanation: Superheat is the amount by which vapor temperature
exceeds its saturation temperature at a given pressure.
, 8. Why should refrigerant tubing be capped during installation?
A. To increase pressure
B. To prevent moisture and contaminants from entering
C. To increase refrigerant velocity
D. To improve thermostat operation
Answer: B
Explanation: Open tubing can allow dirt and moisture into the
refrigeration system.
9. What is the primary purpose of duct insulation on a cold-air duct?
A. Increase refrigerant pressure
B. Reduce unwanted heat gain and condensation
C. Increase gas pressure
D. Increase compressor capacity
Answer: B
Explanation: Insulation limits heat transfer and helps prevent
condensation on cold duct surfaces.
10. What is the function of a reversing valve in a typical heat pump?
A. Controls combustion air
B. Reverses refrigerant flow direction
C. Filters refrigerant
D. Controls condensate
EXAM — VERSION 2 | NEVADA (NV) C-21B AIR CONDITIONING
CONTRACTOR PRACTICE EXAM VERSION 2 — 210 QUESTIONS AND
ANSWERS WITH DETAILED EXPLANATIONS | COMPREHENSIVE HVAC
CONTRACTOR TEST PREPARATION | 2026/2027 UPDATE
1. A properly sized suction line is important primarily because it helps
maintain adequate refrigerant flow and:
A. Prevents all compressor noise
B. Maintains acceptable pressure drop and oil return
C. Eliminates the need for insulation
D. Increases thermostat voltage
Answer: B
Explanation: Proper suction-line sizing helps control pressure loss and
supports reliable refrigerant and oil movement.
2. Which component normally rejects heat absorbed by the refrigerant
from the conditioned space?
A. Evaporator
B. Expansion device
C. Condenser
D. Accumulator
,Answer: C
Explanation: The condenser rejects the heat absorbed in the
evaporator plus the heat added by compressor operation.
3. What is the primary purpose of a thermostat in an HVAC system?
A. Compress refrigerant
B. Sense space temperature and control operation
C. Remove moisture from refrigerant
D. Increase duct pressure
Answer: B
Explanation: A thermostat senses temperature and sends control
signals to operate heating or cooling equipment.
4. Which condition generally increases the cooling load of a building?
A. Improved insulation
B. Reduced solar exposure
C. Increased occupancy
D. Reduced lighting
Answer: C
Explanation: Occupants generate both sensible and latent heat,
increasing the cooling requirement.
5. What is the principal purpose of a filter-drier?
,A. Increase refrigerant pressure
B. Remove moisture and contaminants
C. Increase airflow
D. Control room temperature
Answer: B
Explanation: Filter-driers protect refrigeration components by removing
moisture, acids, and contaminants.
6. A dirty air filter will most commonly cause:
A. Increased airflow
B. Reduced airflow
C. Increased refrigerant charge
D. Increased duct size
Answer: B
Explanation: A dirty filter creates additional resistance to airflow.
7. What is superheat?
A. Liquid refrigerant below saturation temperature
B. Vapor refrigerant above its saturation temperature
C. Air above room temperature
D. Refrigerant pressure above design pressure
Answer: B
Explanation: Superheat is the amount by which vapor temperature
exceeds its saturation temperature at a given pressure.
, 8. Why should refrigerant tubing be capped during installation?
A. To increase pressure
B. To prevent moisture and contaminants from entering
C. To increase refrigerant velocity
D. To improve thermostat operation
Answer: B
Explanation: Open tubing can allow dirt and moisture into the
refrigeration system.
9. What is the primary purpose of duct insulation on a cold-air duct?
A. Increase refrigerant pressure
B. Reduce unwanted heat gain and condensation
C. Increase gas pressure
D. Increase compressor capacity
Answer: B
Explanation: Insulation limits heat transfer and helps prevent
condensation on cold duct surfaces.
10. What is the function of a reversing valve in a typical heat pump?
A. Controls combustion air
B. Reverses refrigerant flow direction
C. Filters refrigerant
D. Controls condensate
