NEVADA (NV) C-21B AIR CONDITIONING CONTRACTOR EXAM TEST
BANK ACTUAL 2026/2027 HIGH YIELD PRACTICE QUESTIONS AND
STUDY GUIDE ACCURATE EXAM
1. A Nevada contractor is reviewing the scope of work permitted under the C-
21B Air-Conditioning classification before accepting a commercial project.
The project involves installing, servicing, repairing, and maintaining air-
conditioning equipment, associated ductwork, thermostatic controls, and
humidity controls used to control air temperature within a building. Which
description most accurately corresponds to the C-21B scope?
A. Fabrication of all sheet-metal products, including gutters, chimneys, and
roofing systems
B. Installation, repair, service, and maintenance of air-conditioning
equipment, related ductwork, and associated humidity and thermostatic
controls
C. Installation of industrial piping used to transport chemicals, food, and
process fluids
D. Installation of only refrigeration equipment designed to maintain
temperatures below 50°F
Answer: B
2. During a planned rooftop replacement, a contractor is asked to install a
complete comfort-cooling system consisting of an outdoor condensing unit,
indoor evaporator coil, refrigerant piping, supply and return ductwork,
thermostat, and humidity-control equipment. The contractor wants to
confirm that the project falls within the appropriate Nevada specialty
classification. Which classification specifically covers this type of work?
A. C-21C Sheet Metal
B. C-21D Maintenance
C. C-21A Refrigeration
D. C-21B Air-Conditioning
Answer: D
pg. 1
, 3. A technician is diagnosing a split-system air conditioner that has a
compressor, condenser coil, metering device, evaporator coil, blower,
thermostat, and refrigerant circuit. The customer reports that the system
runs continuously but the indoor temperature does not reach the
thermostat setting. Before replacing components, which fundamental
refrigeration principle should guide the technician's diagnostic process?
A. Heat naturally moves from a warmer region toward a colder region, and
the refrigeration cycle transfers indoor heat to the outdoor environment
B. Refrigerant permanently destroys indoor heat rather than transferring it
C. The compressor directly converts electrical energy into cold air without
requiring heat transfer
D. The evaporator creates cooling by adding heat to the conditioned space
Answer: A
4. A service technician measures an unusually high suction pressure and low
superheat on a conventional air-conditioning system while the evaporator is
visibly sweating heavily. The airflow across the evaporator is verified to be
adequate, and the metering device is not restricted. Which condition should
be investigated first as a likely cause?
A. Severely undercharged refrigerant circuit
B. Completely blocked condenser coil
C. Excess refrigerant or an overfeeding metering condition
D. Open compressor winding
Answer: C
5. During commissioning of a new split-system air conditioner, the technician
explains that the evaporator coil is the component located in the indoor air
stream. What is the primary function of this coil during normal cooling
operation?
A. Reject heat from the refrigerant to outdoor air
B. Absorb heat from the indoor air and transfer that heat into the
circulating refrigerant
C. Increase compressor discharge pressure by condensing refrigerant vapor
pg. 2
, D. Remove electrical energy from the blower motor
Answer: B
6. A condenser coil becomes heavily contaminated with dirt and debris after
months of operation in a dusty environment. The system continues to run,
but head pressure rises and cooling capacity falls. What is the most direct
reason for the change in operating conditions?
A. Reduced ability of the condenser to reject heat to the outdoor
environment
B. Increased evaporator airflow caused by the dirty coil
C. Increased refrigerant purity caused by the dirt
D. Reduced electrical resistance in the compressor windings
Answer: A
7. A contractor is selecting a compressor for a replacement air-conditioning
system and wants to understand the compressor's fundamental role in the
refrigeration cycle. Which statement most accurately describes its function?
A. It absorbs indoor heat directly from the conditioned room
B. It changes liquid refrigerant into atmospheric moisture
C. It meters refrigerant entering the evaporator
D. It raises the pressure and temperature of refrigerant vapor and circulates
refrigerant through the system
Answer: D
8. A residential system has a thermostatic expansion valve that maintains
controlled refrigerant flow into the evaporator. The technician wants to
understand why superheat is important when evaluating TXV operation.
What does evaporator outlet superheat primarily indicate?
A. The temperature of outdoor air entering the condenser
B. The amount by which refrigerant vapor temperature exceeds its
saturation temperature at that pressure
C. The total electrical current drawn by the compressor
D. The temperature difference between supply and return air only
Answer: B
pg. 3
, 9. A technician is diagnosing a system with a fixed-orifice metering device. The
evaporator pressure is lower than expected and the suction line is unusually
warm. Assuming airflow and condenser conditions are normal, which
condition should be considered?
A. Excessive refrigerant charge caused by liquid flooding
B. An overfed evaporator caused by excessive indoor humidity
C. A restricted metering device or insufficient refrigerant flow into the
evaporator
D. A failed condenser fan that is producing abnormally low head pressure
Answer: C
10. During a maintenance visit, a technician observes frost covering a
substantial portion of the evaporator coil. The customer reports weak
airflow and reduced cooling. The technician measures a very low
temperature difference across the evaporator and discovers a severely
clogged return-air filter. What should be corrected first?
A. Replace the compressor
B. Add refrigerant immediately
C. Replace the condenser fan motor
D. Restore adequate airflow through the evaporator by correcting the filter
restriction
Answer: D
11. A technician is evaluating an air-conditioning system using a refrigerant
pressure-temperature relationship. Why is a pressure-temperature chart
particularly useful during service?
A. It allows the technician to relate measured refrigerant pressure to the
corresponding saturation temperature
B. It determines the exact electrical horsepower of the blower motor
C. It measures duct leakage without testing
D. It determines the building's insulation R-value
Answer: A
pg. 4
BANK ACTUAL 2026/2027 HIGH YIELD PRACTICE QUESTIONS AND
STUDY GUIDE ACCURATE EXAM
1. A Nevada contractor is reviewing the scope of work permitted under the C-
21B Air-Conditioning classification before accepting a commercial project.
The project involves installing, servicing, repairing, and maintaining air-
conditioning equipment, associated ductwork, thermostatic controls, and
humidity controls used to control air temperature within a building. Which
description most accurately corresponds to the C-21B scope?
A. Fabrication of all sheet-metal products, including gutters, chimneys, and
roofing systems
B. Installation, repair, service, and maintenance of air-conditioning
equipment, related ductwork, and associated humidity and thermostatic
controls
C. Installation of industrial piping used to transport chemicals, food, and
process fluids
D. Installation of only refrigeration equipment designed to maintain
temperatures below 50°F
Answer: B
2. During a planned rooftop replacement, a contractor is asked to install a
complete comfort-cooling system consisting of an outdoor condensing unit,
indoor evaporator coil, refrigerant piping, supply and return ductwork,
thermostat, and humidity-control equipment. The contractor wants to
confirm that the project falls within the appropriate Nevada specialty
classification. Which classification specifically covers this type of work?
A. C-21C Sheet Metal
B. C-21D Maintenance
C. C-21A Refrigeration
D. C-21B Air-Conditioning
Answer: D
pg. 1
, 3. A technician is diagnosing a split-system air conditioner that has a
compressor, condenser coil, metering device, evaporator coil, blower,
thermostat, and refrigerant circuit. The customer reports that the system
runs continuously but the indoor temperature does not reach the
thermostat setting. Before replacing components, which fundamental
refrigeration principle should guide the technician's diagnostic process?
A. Heat naturally moves from a warmer region toward a colder region, and
the refrigeration cycle transfers indoor heat to the outdoor environment
B. Refrigerant permanently destroys indoor heat rather than transferring it
C. The compressor directly converts electrical energy into cold air without
requiring heat transfer
D. The evaporator creates cooling by adding heat to the conditioned space
Answer: A
4. A service technician measures an unusually high suction pressure and low
superheat on a conventional air-conditioning system while the evaporator is
visibly sweating heavily. The airflow across the evaporator is verified to be
adequate, and the metering device is not restricted. Which condition should
be investigated first as a likely cause?
A. Severely undercharged refrigerant circuit
B. Completely blocked condenser coil
C. Excess refrigerant or an overfeeding metering condition
D. Open compressor winding
Answer: C
5. During commissioning of a new split-system air conditioner, the technician
explains that the evaporator coil is the component located in the indoor air
stream. What is the primary function of this coil during normal cooling
operation?
A. Reject heat from the refrigerant to outdoor air
B. Absorb heat from the indoor air and transfer that heat into the
circulating refrigerant
C. Increase compressor discharge pressure by condensing refrigerant vapor
pg. 2
, D. Remove electrical energy from the blower motor
Answer: B
6. A condenser coil becomes heavily contaminated with dirt and debris after
months of operation in a dusty environment. The system continues to run,
but head pressure rises and cooling capacity falls. What is the most direct
reason for the change in operating conditions?
A. Reduced ability of the condenser to reject heat to the outdoor
environment
B. Increased evaporator airflow caused by the dirty coil
C. Increased refrigerant purity caused by the dirt
D. Reduced electrical resistance in the compressor windings
Answer: A
7. A contractor is selecting a compressor for a replacement air-conditioning
system and wants to understand the compressor's fundamental role in the
refrigeration cycle. Which statement most accurately describes its function?
A. It absorbs indoor heat directly from the conditioned room
B. It changes liquid refrigerant into atmospheric moisture
C. It meters refrigerant entering the evaporator
D. It raises the pressure and temperature of refrigerant vapor and circulates
refrigerant through the system
Answer: D
8. A residential system has a thermostatic expansion valve that maintains
controlled refrigerant flow into the evaporator. The technician wants to
understand why superheat is important when evaluating TXV operation.
What does evaporator outlet superheat primarily indicate?
A. The temperature of outdoor air entering the condenser
B. The amount by which refrigerant vapor temperature exceeds its
saturation temperature at that pressure
C. The total electrical current drawn by the compressor
D. The temperature difference between supply and return air only
Answer: B
pg. 3
, 9. A technician is diagnosing a system with a fixed-orifice metering device. The
evaporator pressure is lower than expected and the suction line is unusually
warm. Assuming airflow and condenser conditions are normal, which
condition should be considered?
A. Excessive refrigerant charge caused by liquid flooding
B. An overfed evaporator caused by excessive indoor humidity
C. A restricted metering device or insufficient refrigerant flow into the
evaporator
D. A failed condenser fan that is producing abnormally low head pressure
Answer: C
10. During a maintenance visit, a technician observes frost covering a
substantial portion of the evaporator coil. The customer reports weak
airflow and reduced cooling. The technician measures a very low
temperature difference across the evaporator and discovers a severely
clogged return-air filter. What should be corrected first?
A. Replace the compressor
B. Add refrigerant immediately
C. Replace the condenser fan motor
D. Restore adequate airflow through the evaporator by correcting the filter
restriction
Answer: D
11. A technician is evaluating an air-conditioning system using a refrigerant
pressure-temperature relationship. Why is a pressure-temperature chart
particularly useful during service?
A. It allows the technician to relate measured refrigerant pressure to the
corresponding saturation temperature
B. It determines the exact electrical horsepower of the blower motor
C. It measures duct leakage without testing
D. It determines the building's insulation R-value
Answer: A
pg. 4
