NEVADA (NV) C-21B AIR CONDITIONING CONTRACTOR PRACTICE EXAM QUESTIONS AND ANSWERS
ALREADY GRADED A+. 100% VERIFIED SOLUTIONS | UPDATED PER LATEST GUIDELINES | GRADED A+...
Core Domains
Nevada State Contractors Board C-21B Classification and Regulations
Refrigeration Cycle Fundamentals and Thermodynamics
HVAC System Design, Load Calculations, and Equipment Selection
Air Distribution, Ductwork Design, and Ventilation Standards
Refrigerant Handling, EPA Section 608 Certification, and Environmental Compliance
Electrical Controls, Wiring Diagrams, and Troubleshooting
Heating Systems: Gas, Electric, and Heat Pump Operation
International Mechanical Code (IMC) and Nevada Building Code Compliance
Workplace Safety, OSHA Standards, and Confined Space Entry
Nevada Business Law, Contracts, and Lien Requirements for Contractors
Introduction
This practice examination is designed to assess the comprehensive knowledge required for the Nevada C-21B Air
Conditioning Contractor license. The exam evaluates competencies in the installation, maintenance, and repair of
residential and light commercial air conditioning and heating systems, including refrigeration cycles, heat pump
operation, gas heating, air distribution, and control systems. The 100-question multiple-choice format includes
scenario-based questions that test the application of thermodynamics principles, the International Mechanical
Code, EPA refrigerant regulations, and safe work practices to real-world HVAC service situations. Candidates must
,demonstrate critical thinking in diagnosing system faults, performing load calculations, sizing ductwork, and
selecting appropriate equipment. Mastery of this material confirms the professional decision-making skills
necessary to operate as a licensed air conditioning contractor in the State of Nevada.
SECTION ONE
Question 1
According to the Nevada State Contractors Board, the C-21B classification authorizes a licensed contractor to
perform which scope of work?
A. Only commercial refrigeration systems
B. The installation, modification, and repair of air conditioning, heating, ventilation, and evaporative cooling
systems in residential and light commercial applications
C. Only the installation of sheet metal ductwork
D. Electrical wiring of any voltage system
🟢 Correct Answer:
B
🔴 RATIONALE:
The Nevada C-21B classification covers the full scope of residential and light commercial HVAC work, including
air conditioning, warm-air heating, ventilation, and evaporative cooling systems. It is distinct from the C-21A
(Refrigeration) classification and general electrical classifications.
,Question 2
In a vapor-compression refrigeration cycle, what is the function of the compressor?
A. To absorb heat from the conditioned space
B. To increase the pressure and temperature of the refrigerant vapor and circulate it through the system
C. To reject heat to the outdoor air
D. To regulate the flow of refrigerant to the evaporator
🟢 Correct Answer:
B
🔴 RATIONALE):
The compressor is the heart of the refrigeration cycle. It pulls low-pressure, low-temperature vapor from the
evaporator and compresses it into a high-pressure, high-temperature vapor. This enables heat rejection at the
condenser and provides the pressure differential that drives refrigerant flow.
Question 3
What is the primary purpose of a thermostatic expansion valve (TXV) in an air conditioning system?
A. To turn the compressor on and off
B. To regulate the flow of liquid refrigerant into the evaporator based on the superheat at the evaporator outlet,
maintaining optimum coil efficiency
C. To filter contaminants from the refrigerant
D. To store excess refrigerant during low-load conditions
, 🟢 Correct Answer:
B
🔴 RATIONALE):
A TXV is a modulating metering device that controls refrigerant flow to the evaporator. It senses the suction line
temperature and pressure at the evaporator outlet, adjusting the flow to maintain a constant, safe superheat,
ensuring the evaporator is fully utilized without flooding liquid to the compressor.
Question 4
Under the EPA Section 608 regulations, what is the maximum allowable annual leak rate for comfort cooling
appliances containing 50 or more pounds of refrigerant before repair is mandatory?
A. 5%
B. 10%
C. 15%
D. 20%
🟢 Correct Answer:
B
🔴 RATIONALE):
EPA regulations require that comfort cooling appliances with a charge of 50 pounds or more that leak at a rate
of 10% or more per year must be repaired within 30 days, or a retrofit or retirement plan must be developed.
ALREADY GRADED A+. 100% VERIFIED SOLUTIONS | UPDATED PER LATEST GUIDELINES | GRADED A+...
Core Domains
Nevada State Contractors Board C-21B Classification and Regulations
Refrigeration Cycle Fundamentals and Thermodynamics
HVAC System Design, Load Calculations, and Equipment Selection
Air Distribution, Ductwork Design, and Ventilation Standards
Refrigerant Handling, EPA Section 608 Certification, and Environmental Compliance
Electrical Controls, Wiring Diagrams, and Troubleshooting
Heating Systems: Gas, Electric, and Heat Pump Operation
International Mechanical Code (IMC) and Nevada Building Code Compliance
Workplace Safety, OSHA Standards, and Confined Space Entry
Nevada Business Law, Contracts, and Lien Requirements for Contractors
Introduction
This practice examination is designed to assess the comprehensive knowledge required for the Nevada C-21B Air
Conditioning Contractor license. The exam evaluates competencies in the installation, maintenance, and repair of
residential and light commercial air conditioning and heating systems, including refrigeration cycles, heat pump
operation, gas heating, air distribution, and control systems. The 100-question multiple-choice format includes
scenario-based questions that test the application of thermodynamics principles, the International Mechanical
Code, EPA refrigerant regulations, and safe work practices to real-world HVAC service situations. Candidates must
,demonstrate critical thinking in diagnosing system faults, performing load calculations, sizing ductwork, and
selecting appropriate equipment. Mastery of this material confirms the professional decision-making skills
necessary to operate as a licensed air conditioning contractor in the State of Nevada.
SECTION ONE
Question 1
According to the Nevada State Contractors Board, the C-21B classification authorizes a licensed contractor to
perform which scope of work?
A. Only commercial refrigeration systems
B. The installation, modification, and repair of air conditioning, heating, ventilation, and evaporative cooling
systems in residential and light commercial applications
C. Only the installation of sheet metal ductwork
D. Electrical wiring of any voltage system
🟢 Correct Answer:
B
🔴 RATIONALE:
The Nevada C-21B classification covers the full scope of residential and light commercial HVAC work, including
air conditioning, warm-air heating, ventilation, and evaporative cooling systems. It is distinct from the C-21A
(Refrigeration) classification and general electrical classifications.
,Question 2
In a vapor-compression refrigeration cycle, what is the function of the compressor?
A. To absorb heat from the conditioned space
B. To increase the pressure and temperature of the refrigerant vapor and circulate it through the system
C. To reject heat to the outdoor air
D. To regulate the flow of refrigerant to the evaporator
🟢 Correct Answer:
B
🔴 RATIONALE):
The compressor is the heart of the refrigeration cycle. It pulls low-pressure, low-temperature vapor from the
evaporator and compresses it into a high-pressure, high-temperature vapor. This enables heat rejection at the
condenser and provides the pressure differential that drives refrigerant flow.
Question 3
What is the primary purpose of a thermostatic expansion valve (TXV) in an air conditioning system?
A. To turn the compressor on and off
B. To regulate the flow of liquid refrigerant into the evaporator based on the superheat at the evaporator outlet,
maintaining optimum coil efficiency
C. To filter contaminants from the refrigerant
D. To store excess refrigerant during low-load conditions
, 🟢 Correct Answer:
B
🔴 RATIONALE):
A TXV is a modulating metering device that controls refrigerant flow to the evaporator. It senses the suction line
temperature and pressure at the evaporator outlet, adjusting the flow to maintain a constant, safe superheat,
ensuring the evaporator is fully utilized without flooding liquid to the compressor.
Question 4
Under the EPA Section 608 regulations, what is the maximum allowable annual leak rate for comfort cooling
appliances containing 50 or more pounds of refrigerant before repair is mandatory?
A. 5%
B. 10%
C. 15%
D. 20%
🟢 Correct Answer:
B
🔴 RATIONALE):
EPA regulations require that comfort cooling appliances with a charge of 50 pounds or more that leak at a rate
of 10% or more per year must be repaired within 30 days, or a retrofit or retirement plan must be developed.
