Nevada (NV) C-21B Air Conditioning Contractor State Licensing Practice Exam Exam 2026 – Actual Questions with Answers & Explanations | INSTANT PDF DOWNLOAD

Nevada (NV) C-21B Air Conditioning Contractor State
Licensing Practice Exam Exam 2026 – Actual
Questions with Answers & Explanations | INSTANT
PDF DOWNLOAD




1: Refrigeration Theory & System Components
1. In a standard compression refrigeration cycle, where is the refrigerant a high-
pressure, superheated gas?

 A) Leaving the evaporator

 B) Leaving the expansion valve

 C) Leaving the compressor

 D) Leaving the condenser

Explanation: The compressor takes in low-pressure vapor and compresses it, which
significantly increases both its pressure and temperature, resulting in a high-pressure,
superheated gas.


2. Which component is responsible for changing a low-pressure liquid into a
low-pressure gas by absorbing heat?

 A) Evaporator

 B) Condenser

 C) Accumulator

 D) Receiver

, Explanation: The evaporator is the heat-exchange surface where the liquid refrigerant
boils (evaporates) as it absorbs heat from the indoor air or medium being cooled.


3. What is the purpose of the "Subcooling" measurement in an air
conditioning system?

 A) To ensure the compressor is not overheating

 B) To confirm that the condenser has rejected enough heat to turn all gas into a
liquid

 C) To measure the efficiency of the air filter

 D) To check the humidity levels in the ductwork

Explanation: Subcooling is the temperature of a liquid below its saturation point. High
subcooling confirms that the refrigerant leaving the condenser is 100% liquid before it
reaches the metering device.


4. A TXV (Thermostatic Expansion Valve) regulates refrigerant flow based on
which input?

 A) High-side pressure

 B) Evaporator outlet superheat

 C) Outdoor ambient temperature

 D) Compressor oil level

Explanation: The TXV senses the temperature at the tailpipe of the evaporator using a
sensing bulb to maintain a constant superheat, ensuring the evaporator is fed correctly
without flooding the compressor.


5. What is the primary function of a "Filter Drier" installed in the liquid line?

 A) To regulate the pressure of the refrigerant

 B) To act as a secondary condenser

 C) To remove moisture and contaminants from the refrigerant

, D) To muffle the sound of the compressor

Explanation: Moisture in a refrigeration system can create acid or ice crystals. The filter
drier contains desiccant material to trap moisture and a filter to catch debris like copper
shavings or scale.


6. If a system has a "Low Superheat" reading, what is a likely cause?

 A) The system is low on charge

 B) There is a restriction in the liquid line

 C) An overfed evaporator (liquid reaching the compressor)

 D) The outdoor fan motor is failing

Explanation: Low superheat means the refrigerant is not picking up enough heat in the
evaporator, often caused by a dirty air filter, a failing blower motor, or an overcharged
system.


7. Which type of compressor uses a "Rotating Offset Roller" to compress
refrigerant?

 A) Reciprocating

 B) Rotary

 C) Centrifugal

 D) Screw

Explanation: Rotary compressors are common in smaller residential units and window
air conditioners. They use a rotating cylinder or roller to trap and compress the gas.


8. "Sensible Heat" is defined as heat that results in:

 A) A change in the state of a substance (liquid to gas)

 B) A change in the temperature of a substance that can be measured by a
thermometer

 C) The moisture content in the air

,  D) The pressure of the refrigerant in the condenser

Explanation: Sensible heat is heat you can "sense" or measure with a thermometer.
Unlike latent heat (which changes the state), sensible heat directly increases or
decreases the temperature of the substance.


9. In a heat pump system, which component allows the unit to switch between
heating and cooling modes?

 A) The Defrost Timer

 B) The Reversing Valve

 C) The Crankcase Heater

 D) The Bi-flow Filter Drier

Explanation: The reversing valve (or four-way valve) changes the direction of
refrigerant flow, making the indoor coil the condenser in heating mode and the
evaporator in cooling mode.


10. What does the acronym "SEER" stand for in HVAC terminology?

 A) System Energy Exchange Ratio

 B) Seasonal Energy Efficiency Ratio

 C) Standard Electric Evaporation Rating

 D) Secondary Environmental Energy Release

Explanation: SEER is the standard rating for the efficiency of air conditioners. A higher
SEER rating indicates a more energy-efficient unit that uses less electricity to provide
the same amount of cooling.
11. Which refrigerant is a Hydrofluorocarbon (HFC) commonly used in
residential AC systems that does not deplete the ozone layer?

 A) R-22

 B) R-410A

 C) R-12