NEVADA C-21B AIR CONDITIONING CONTRACTOR
ACTUAL PRACTICE EXAM 2026/2027 QUESTIONS
WITH VERIFIED ANSWERS | INSTANT DOWNLOAD
PDF
Overview:
This Actual exam is designed to help candidates prepare for the Nevada C-21B Air Conditioning
Contractor licensing exam. covering:
Refrigeration and heat pump theory
System components (compressors, condensers, evaporators, expansion devices, etc.)
Electrical controls, motors, and capacitors
Duct design, airflow, and insulation
Refrigerant handling, charging, and safety
Troubleshooting and maintenance procedures
Energy efficiency, load calculations, and system performance
Codes, regulations, and best practices for Nevada AC installations
Each question includes the correct answer and a brief rationale to reinforce understanding and
exam readiness.
1. What is the primary purpose of a condenser in an air conditioning system?
A. To evaporate refrigerant
B. To absorb heat from the indoor air
C. To release heat to the outside environment
D. To compress the refrigerant
Rationale: The condenser removes heat from the refrigerant, allowing it to condense back into
liquid form.
2. Which type of refrigerant is commonly used in modern residential air conditioning
systems?
A. R-22
B. R-410A
C. R-12
D. Ammonia
Rationale: R-410A is widely used today due to its efficiency and compliance with
environmental regulations.
,3. What is the standard voltage for most residential AC units in Nevada?
A. 120 V
B. 240 V
C. 208 V
D. 480 V
Rationale: Most residential air conditioners in the U.S. operate on 240 V.
4. Which component regulates refrigerant flow into the evaporator?
A. Compressor
B. Expansion valve
C. Condenser coil
D. Filter dryer
Rationale: The expansion valve controls refrigerant entering the evaporator for proper cooling.
5. What is the purpose of a metering device?
A. To increase airflow
B. To reduce pressure and control refrigerant flow
C. To heat refrigerant
D. To filter debris
Rationale: It lowers refrigerant pressure before entering the evaporator, allowing efficient heat
absorption.
6. In HVAC, SEER stands for:
A. Seasonal Energy Efficiency Ratio
B. Standard Electrical Efficiency Rating
C. Seasonal Energy Efficiency Ratio
D. Standard Equipment Efficiency Ratio
Rationale: SEER measures air conditioner efficiency over a cooling season.
7. What is the first step in troubleshooting a non-operational AC unit?
A. Replace the compressor
B. Check the power supply and circuit breakers
C. Evacuate refrigerant
D. Clean the condenser coil
Rationale: Ensuring the unit has power is the first and safest step.
8. The evaporator coil is located:
A. Outside the building
B. In the condenser
C. Inside the air handler or furnace
,D. Next to the compressor
Rationale: The evaporator absorbs heat from indoor air and is located inside the air handler.
9. What type of system uses water as the cooling medium instead of air?
A. Split system
B. Packaged AC
C. Chiller system
D. Heat pump
Rationale: Chillers circulate chilled water to fan coil units or air handlers.
10. Which safety device protects an AC compressor from electrical overload?
A. Capacitor
B. Circuit breaker or overload protector
C. Expansion valve
D. Thermostat
Rationale: Overload protectors prevent damage from excessive current.
11. What does a high superheat reading indicate?
A. Overcharged system
B. Undercharged system or restricted flow
C. Normal operation
D. Low indoor temperature
Rationale: High superheat often means insufficient refrigerant reaching the evaporator.
12. The function of a filter drier is to:
A. Increase refrigerant pressure
B. Add lubricant
C. Remove moisture and contaminants
D. Evaporate refrigerant
Rationale: Moisture in the system can cause freezing or corrosion; filter driers prevent this.
13. In air conditioning, latent heat refers to:
A. Heat sensed by a thermometer
B. Heat generated by the compressor
C. Heat absorbed or released during phase change
D. Heat lost through duct leaks
Rationale: Latent heat is energy used to change the refrigerant from liquid to vapor.
14. Which tool is used to check refrigerant pressure?
, A. Multimeter
B. Thermometer
C. Manifold gauge set
D. Anemometer
Rationale: Manifold gauges measure high- and low-side pressures in an AC system.
15. What is the typical airflow in a residential supply duct?
A. 200–400 CFM per ton
B. 300–500 CFM per ton
C. 400–500 CFM per ton
D. 500–600 CFM per ton
Rationale: 400–500 CFM per ton is standard for balanced airflow in most systems.
16. Which refrigerant is considered ozone-depleting and being phased out?
A. R-410A
B. R-134a
C. R-22
D. R-407C
Rationale: R-22 is an HCFC, being replaced due to environmental regulations.
17. What is the recommended minimum insulation value for HVAC ductwork in
unconditioned spaces?
A. R-2
B. R-4
C. R-6
D. R-8
Rationale: R-6 is typical for ducts in unconditioned attics or crawlspaces.
18. Which component compresses refrigerant in a vapor-compression cycle?
A. Condenser
B. Expansion valve
C. Compressor
D. Evaporator
Rationale: The compressor increases refrigerant pressure, circulating it through the system.
19. What is the main purpose of a cooling tower in a commercial AC system?
A. To cool the refrigerant directly
B. To supply hot water
C. To reject heat from water-cooled condensers
D. To filter air
Rationale: Cooling towers remove heat from condenser water in large systems.
ACTUAL PRACTICE EXAM 2026/2027 QUESTIONS
WITH VERIFIED ANSWERS | INSTANT DOWNLOAD
Overview:
This Actual exam is designed to help candidates prepare for the Nevada C-21B Air Conditioning
Contractor licensing exam. covering:
Refrigeration and heat pump theory
System components (compressors, condensers, evaporators, expansion devices, etc.)
Electrical controls, motors, and capacitors
Duct design, airflow, and insulation
Refrigerant handling, charging, and safety
Troubleshooting and maintenance procedures
Energy efficiency, load calculations, and system performance
Codes, regulations, and best practices for Nevada AC installations
Each question includes the correct answer and a brief rationale to reinforce understanding and
exam readiness.
1. What is the primary purpose of a condenser in an air conditioning system?
A. To evaporate refrigerant
B. To absorb heat from the indoor air
C. To release heat to the outside environment
D. To compress the refrigerant
Rationale: The condenser removes heat from the refrigerant, allowing it to condense back into
liquid form.
2. Which type of refrigerant is commonly used in modern residential air conditioning
systems?
A. R-22
B. R-410A
C. R-12
D. Ammonia
Rationale: R-410A is widely used today due to its efficiency and compliance with
environmental regulations.
,3. What is the standard voltage for most residential AC units in Nevada?
A. 120 V
B. 240 V
C. 208 V
D. 480 V
Rationale: Most residential air conditioners in the U.S. operate on 240 V.
4. Which component regulates refrigerant flow into the evaporator?
A. Compressor
B. Expansion valve
C. Condenser coil
D. Filter dryer
Rationale: The expansion valve controls refrigerant entering the evaporator for proper cooling.
5. What is the purpose of a metering device?
A. To increase airflow
B. To reduce pressure and control refrigerant flow
C. To heat refrigerant
D. To filter debris
Rationale: It lowers refrigerant pressure before entering the evaporator, allowing efficient heat
absorption.
6. In HVAC, SEER stands for:
A. Seasonal Energy Efficiency Ratio
B. Standard Electrical Efficiency Rating
C. Seasonal Energy Efficiency Ratio
D. Standard Equipment Efficiency Ratio
Rationale: SEER measures air conditioner efficiency over a cooling season.
7. What is the first step in troubleshooting a non-operational AC unit?
A. Replace the compressor
B. Check the power supply and circuit breakers
C. Evacuate refrigerant
D. Clean the condenser coil
Rationale: Ensuring the unit has power is the first and safest step.
8. The evaporator coil is located:
A. Outside the building
B. In the condenser
C. Inside the air handler or furnace
,D. Next to the compressor
Rationale: The evaporator absorbs heat from indoor air and is located inside the air handler.
9. What type of system uses water as the cooling medium instead of air?
A. Split system
B. Packaged AC
C. Chiller system
D. Heat pump
Rationale: Chillers circulate chilled water to fan coil units or air handlers.
10. Which safety device protects an AC compressor from electrical overload?
A. Capacitor
B. Circuit breaker or overload protector
C. Expansion valve
D. Thermostat
Rationale: Overload protectors prevent damage from excessive current.
11. What does a high superheat reading indicate?
A. Overcharged system
B. Undercharged system or restricted flow
C. Normal operation
D. Low indoor temperature
Rationale: High superheat often means insufficient refrigerant reaching the evaporator.
12. The function of a filter drier is to:
A. Increase refrigerant pressure
B. Add lubricant
C. Remove moisture and contaminants
D. Evaporate refrigerant
Rationale: Moisture in the system can cause freezing or corrosion; filter driers prevent this.
13. In air conditioning, latent heat refers to:
A. Heat sensed by a thermometer
B. Heat generated by the compressor
C. Heat absorbed or released during phase change
D. Heat lost through duct leaks
Rationale: Latent heat is energy used to change the refrigerant from liquid to vapor.
14. Which tool is used to check refrigerant pressure?
, A. Multimeter
B. Thermometer
C. Manifold gauge set
D. Anemometer
Rationale: Manifold gauges measure high- and low-side pressures in an AC system.
15. What is the typical airflow in a residential supply duct?
A. 200–400 CFM per ton
B. 300–500 CFM per ton
C. 400–500 CFM per ton
D. 500–600 CFM per ton
Rationale: 400–500 CFM per ton is standard for balanced airflow in most systems.
16. Which refrigerant is considered ozone-depleting and being phased out?
A. R-410A
B. R-134a
C. R-22
D. R-407C
Rationale: R-22 is an HCFC, being replaced due to environmental regulations.
17. What is the recommended minimum insulation value for HVAC ductwork in
unconditioned spaces?
A. R-2
B. R-4
C. R-6
D. R-8
Rationale: R-6 is typical for ducts in unconditioned attics or crawlspaces.
18. Which component compresses refrigerant in a vapor-compression cycle?
A. Condenser
B. Expansion valve
C. Compressor
D. Evaporator
Rationale: The compressor increases refrigerant pressure, circulating it through the system.
19. What is the main purpose of a cooling tower in a commercial AC system?
A. To cool the refrigerant directly
B. To supply hot water
C. To reject heat from water-cooled condensers
D. To filter air
Rationale: Cooling towers remove heat from condenser water in large systems.
