NEVADA C-21B AIR-CONDITIONING CONTRACTOR EXAMINATION
UPDATED QUESTIONS AND ANSWERS WITH RATIONALE
A+ GRADED| BRAND NEW RELEASE!
This comprehensive test bank is designed to prepare candidates for the Nevada C-21B
Air-Conditioning Contractor Examination. This resource contains 250 questions, each
with a correct answer and a short rationale to reinforce learning and understanding of
core concepts. The questions cover essential topics required for professional practice
as an air-conditioning contractor in Nevada.
DOMAINS COVERED
1. Refrigeration Cycle Fundamentals — evaporator, compressor, condenser, metering
devices, and refrigerant properties.
2. Heat Transfer Principles — sensible and latent heat, conduction, convection,
radiation, and psychrometrics.
3. Electrical Systems — motors, controls, wiring, transformers, relays, and safety
devices.
4. Duct Design and Air Distribution — sizing, friction loss, static pressure, airflow, and
duct materials.
5. System Installation — equipment placement, refrigerant piping, brazing,
evacuation, and charging.
6. Troubleshooting and Diagnostics — pressure-temperature relationships, superheat,
subcooling, and electrical troubleshooting.
7. Safety and Refrigerant Handling — EPA regulations, refrigerant recovery, safe
handling, and personal protective equipment.
8. Heating Systems — furnaces, heat pumps, electric heat, and gas-fired equipment.
9. Nevada Building Codes and Regulations — state codes, permitting, inspections,
and contractor licensing.
10. Load Calculations and System Sizing — Manual J, Manual D, Manual S, and
equipment selection.
,EXAMINATION QUESTIONS AND SOLUTIONS
1. What is the primary purpose of an evaporator in a conventional vapor-
compression air-conditioning system?
A. Reject heat into outdoor air
B. Absorb heat from the conditioned space
C. Increase refrigerant pressure
D. Store liquid refrigerant
Answer: B
Rationale: The evaporator absorbs heat from indoor air as refrigerant changes
from liquid to vapor, thereby producing the desired cooling effect.
2. Which component normally raises refrigerant vapor from evaporator pressure to
condenser pressure?
A. Expansion valve
B. Filter-drier
C. Compressor
D. Receiver
Answer: C
Rationale: The compressor increases refrigerant vapor pressure and temperature
while moving refrigerant through the refrigeration cycle toward the condenser.
3. What occurs when refrigerant passes through a properly operating metering
device?
,A. Pressure increases substantially
B. Pressure drops and refrigerant begins evaporating
C. Vapor becomes completely superheated immediately
D. Condenser pressure increases
Answer: B
Rationale: The metering device creates a pressure drop that allows high-pressure
liquid refrigerant to enter the lower-pressure evaporator.
4. What is sensible heat?
A. Heat associated with a phase change
B. Heat that changes temperature without changing physical state
C. Heat produced exclusively by combustion
D. Heat contained only in refrigerant
Answer: B
Rationale: Sensible heat changes the measurable temperature of a substance
without causing a change between solid, liquid, or vapor states.
5. What is latent heat primarily associated with?
A. Temperature measurement
B. Phase change
C. Electrical resistance
D. Air velocity
Answer: B
Rationale: Latent heat is energy absorbed or released during a phase change while
the substance's temperature remains essentially constant.
, 6. What generally happens to refrigerant saturation temperature when pressure
increases?
A. It decreases
B. It remains unchanged
C. It increases
D. It becomes impossible to determine
Answer: C
Rationale: For a given refrigerant, higher saturation pressure corresponds to higher
saturation temperature according to its pressure-temperature relationship.
7. Why is superheat measured at the evaporator outlet or suction line?
A. To determine condenser capacity
B. To verify that liquid refrigerant is not entering the compressor
C. To measure indoor humidity directly
D. To calculate duct friction
Answer: B
Rationale: Adequate suction superheat helps confirm that refrigerant leaving the
evaporator is vapor rather than potentially damaging liquid entering the
compressor.
8. What does subcooling describe in a refrigeration system?
A. Vapor above its saturation temperature
B. Liquid below its saturation temperature
C. Air below freezing
UPDATED QUESTIONS AND ANSWERS WITH RATIONALE
A+ GRADED| BRAND NEW RELEASE!
This comprehensive test bank is designed to prepare candidates for the Nevada C-21B
Air-Conditioning Contractor Examination. This resource contains 250 questions, each
with a correct answer and a short rationale to reinforce learning and understanding of
core concepts. The questions cover essential topics required for professional practice
as an air-conditioning contractor in Nevada.
DOMAINS COVERED
1. Refrigeration Cycle Fundamentals — evaporator, compressor, condenser, metering
devices, and refrigerant properties.
2. Heat Transfer Principles — sensible and latent heat, conduction, convection,
radiation, and psychrometrics.
3. Electrical Systems — motors, controls, wiring, transformers, relays, and safety
devices.
4. Duct Design and Air Distribution — sizing, friction loss, static pressure, airflow, and
duct materials.
5. System Installation — equipment placement, refrigerant piping, brazing,
evacuation, and charging.
6. Troubleshooting and Diagnostics — pressure-temperature relationships, superheat,
subcooling, and electrical troubleshooting.
7. Safety and Refrigerant Handling — EPA regulations, refrigerant recovery, safe
handling, and personal protective equipment.
8. Heating Systems — furnaces, heat pumps, electric heat, and gas-fired equipment.
9. Nevada Building Codes and Regulations — state codes, permitting, inspections,
and contractor licensing.
10. Load Calculations and System Sizing — Manual J, Manual D, Manual S, and
equipment selection.
,EXAMINATION QUESTIONS AND SOLUTIONS
1. What is the primary purpose of an evaporator in a conventional vapor-
compression air-conditioning system?
A. Reject heat into outdoor air
B. Absorb heat from the conditioned space
C. Increase refrigerant pressure
D. Store liquid refrigerant
Answer: B
Rationale: The evaporator absorbs heat from indoor air as refrigerant changes
from liquid to vapor, thereby producing the desired cooling effect.
2. Which component normally raises refrigerant vapor from evaporator pressure to
condenser pressure?
A. Expansion valve
B. Filter-drier
C. Compressor
D. Receiver
Answer: C
Rationale: The compressor increases refrigerant vapor pressure and temperature
while moving refrigerant through the refrigeration cycle toward the condenser.
3. What occurs when refrigerant passes through a properly operating metering
device?
,A. Pressure increases substantially
B. Pressure drops and refrigerant begins evaporating
C. Vapor becomes completely superheated immediately
D. Condenser pressure increases
Answer: B
Rationale: The metering device creates a pressure drop that allows high-pressure
liquid refrigerant to enter the lower-pressure evaporator.
4. What is sensible heat?
A. Heat associated with a phase change
B. Heat that changes temperature without changing physical state
C. Heat produced exclusively by combustion
D. Heat contained only in refrigerant
Answer: B
Rationale: Sensible heat changes the measurable temperature of a substance
without causing a change between solid, liquid, or vapor states.
5. What is latent heat primarily associated with?
A. Temperature measurement
B. Phase change
C. Electrical resistance
D. Air velocity
Answer: B
Rationale: Latent heat is energy absorbed or released during a phase change while
the substance's temperature remains essentially constant.
, 6. What generally happens to refrigerant saturation temperature when pressure
increases?
A. It decreases
B. It remains unchanged
C. It increases
D. It becomes impossible to determine
Answer: C
Rationale: For a given refrigerant, higher saturation pressure corresponds to higher
saturation temperature according to its pressure-temperature relationship.
7. Why is superheat measured at the evaporator outlet or suction line?
A. To determine condenser capacity
B. To verify that liquid refrigerant is not entering the compressor
C. To measure indoor humidity directly
D. To calculate duct friction
Answer: B
Rationale: Adequate suction superheat helps confirm that refrigerant leaving the
evaporator is vapor rather than potentially damaging liquid entering the
compressor.
8. What does subcooling describe in a refrigeration system?
A. Vapor above its saturation temperature
B. Liquid below its saturation temperature
C. Air below freezing
