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Nevada C-21 Refrigeration & Air Conditioning Maintenance Contractor Practice Exam This comprehensive practice exam is designed for candidates seeking the Nevada C- 21 Refrigeration and Air Conditioning Contractor license, with special emphasis on the C-21d Maintenance subclassification. The questions cover the official scope of work, technical knowledge, safety regulations, and business management requirements as defined by the Nevada State Contractors Board (NSCB) and industry standards. EXAM FORMAT & ADMINISTRATIVE REQUIREMENTS Question 1: What is the minimum amount of relevant work experience required to qualify for a Nevada C-21 Refrigeration and Air Conditioning Contractor license? A) 2 years B) 3 years C) 4 years D) 5 years Correct Answer: C) 4 years Rationale: Applicants must document a minimum of four years of experience within the past 10 years working as a journeyman, foreman, supervisor, or contractor in the HVAC field. Formal training from an approved school may count for up to three years of this experience.
Question 2: How many questions are on the C-21 trade exam, and what is the passing score?
A) 60 questions, 75% passing (45 correct) B) 85 questions, 70% passing (60 correct) C) 50 questions, 70% passing (35 correct) D) 100 questions, 80% passing (80 correct) Correct Answer: B) 85 questions, 70% passing (60 correct) Rationale: The C-21 trade exam consists of 85 questions, and candidates must answer at least 60 questions correctly to pass. Both the trade exam and the Contractor Management Survey Exam are open-book tests.
Question 3: Which two exams are required to obtain a C-21 license in Nevada? A) EPA Section 608 and OSHA 30 B) Contractor Management Survey Exam and C-21 Trade Exam C) Business Law Exam and NEC Exam D) Mechanical Code Exam and Energy Efficiency Exam Correct Answer: B) Contractor Management Survey Exam and C-21 Trade Exam Rationale: Candidates must pass the Contractor Management Survey Exam (business and law topics) and the C-21 Trade Exam (technical HVAC content).
Question 6: A C-21 license holder who wants to perform work on swimming pool heaters and associated gas piping should also hold which additional license? A) C-1 (General Engineering) B) C-1D (Plumbing & Heating) C) C-2 (Residential) D) C-20 (Tiling) Correct Answer: B) C-1D (Plumbing & Heating) Rationale: The C-1D classification covers plumbing, water heaters, and gas piping. A contractor with both C-21 and C-1D can handle HVAC and plumbing needs under one roof.
Question 7: What is the maximum bid limit for a C-21 license holder? A) $250, B) $500, C) $700, D) No fixed limit Correct Answer: C) $700,
Rationale: A C-21 license typically has a bid limit of $700,000, though this may vary based on the contractor's financial qualifications and bonding.
Question 8: According to NAC 624.380, work authorized by a classification C-21 license is: A) Incidental to the performance of any other work B) Not incidental or supplemental to the performance of any other work C) Only supplemental to plumbing work D) Only allowed for residential projects Correct Answer: B) Not incidental or supplemental to the performance of any other work Rationale: Nevada Administrative Code explicitly states that work authorized by a C-21 license is not incidental or supplemental to the performance of any other work which may be performed by a specialty contractor.
Question 9: Which C-21 subclassification specifically covers the repair and replacement of parts of existing units, including compressors, motors, and coils, but not complete condenser assembly replacement? A) C-21a (Refrigeration) B) C-21b (Air-Conditioning) C) C-21c (Sheet Metal)
Question 11: A contractor wants to install a new ductless mini-split system in a residential home. Which subclassification is most appropriate? A) C-21a (Refrigeration) B) C-21b (Air-Conditioning) C) C-21d (Maintenance) D) C-21f (Chilled and Hot Water Systems) Correct Answer: B) C-21b (Air-Conditioning) Rationale: Subclassification C-21b covers installation, repair, service, and maintenance of equipment that uses evaporation, refrigeration, boilers, or combustion for air temperature control in structures.
Question 12: What type of work is NOT permitted under the C-21d Maintenance subclassification? A) Compressor replacement B) Motor replacement C) Replacement of complete condenser assemblies on remote systems D) Coil replacement Correct Answer: C) Replacement of complete condenser assemblies on remote systems
Rationale: The C-21d classification explicitly excludes replacement of complete condenser assemblies on remote systems, air handlers, or any work that may alter the design of an existing system.
PART 2: REFRIGERATION CYCLE & SYSTEM COMPONENTS
Question 13: Which of the following best describes the function of a compressor in a refrigeration or air conditioning system? A) It condenses the refrigerant from a gas to a liquid B) It expands the refrigerant to lower its pressure C) It raises the pressure and temperature of the refrigerant vapor D) It absorbs heat from the surrounding air Correct Answer: C) It raises the pressure and temperature of the refrigerant vapor Rationale: The compressor's role is to compress (raise the pressure of) the refrigerant vapor, which also increases its temperature so it can release heat in the condenser.
Question 14: A condenser in a refrigeration cycle typically: A) Removes latent heat from the refrigerant, causing it to boil B) Removes latent heat from the refrigerant, causing it to condense
A) Temperature of refrigerant above its saturation temperature at a given pressure B) Temperature of refrigerant below its saturation temperature at a given pressure C) The difference between refrigerant pressure and atmospheric pressure D) The amount of heat removed from the condenser coil Correct Answer: A) Temperature of refrigerant above its saturation temperature at a given pressure Rationale: Superheat is the temperature rise of vapor refrigerant above its boiling point at the same pressure, ensuring only vapor enters the compressor.
Question 17: Subcooling in a refrigeration system refers to: A) Cooling the refrigerant below saturation temperature after it condenses B) Overheating the refrigerant vapor C) The evaporator operating below freezing D) Using additional fans to reduce humidity Correct Answer: A) Cooling the refrigerant below saturation temperature after it condenses Rationale: Subcooling occurs when liquid refrigerant temperature is reduced below its saturation temperature at a given pressure, increasing system efficiency and preventing flash gas at the metering device.
Question 18: Which refrigerant has been widely phased out due to high ozone depletion potential (ODP)? A) R-410A B) R-134a C) R-12 (CFC-12) D) R- 32 Correct Answer: C) R-12 (CFC-12) Rationale: R-12, a CFC refrigerant, has a high ODP and has been largely phased out under the Montreal Protocol.
Question 19: Which refrigerant is a low-global-warming-potential (GWP) alternative to R-410A? A) R- 22 B) R-134a C) R- 32 D) R- 12 Correct Answer: C) R- 32 Rationale: R-32 has a GWP of about 675, considerably lower than R-410A's GWP of approximately 2088, making it a lower-impact alternative.
Rationale: A crankcase heater keeps the refrigerant from migrating and condensing in the compressor's crankcase, preventing slugging on startup.
Question 22: What is the function of an oil separator in a refrigeration system? A) Lower the pressure of the refrigerant B) Reduce the noise produced by the compressor C) Remove and return compressor oil from the discharge gas D) Improve indoor air quality by filtering the air Correct Answer: C) Remove and return compressor oil from the discharge gas Rationale: The oil separator returns entrained oil from the discharge gas to the compressor's crankcase, maintaining lubrication and preventing oil circulation in the system.
Question 23: Latent heat in the context of HVAC generally refers to: A) The heat released due to a change in pressure B) The heat needed to change the state of a substance without a temperature change C) Heat that only exists in cold environments D) A type of heat measured only above 100°F
Correct Answer: B) The heat needed to change the state of a substance without a temperature change Rationale: Latent heat is the energy absorbed or released during a phase change (e.g., liquid to vapor) at constant temperature.
Question 24: Sensible heat in an HVAC system is: A) Heat that does not lead to a temperature change B) Heat that results in a measurable temperature change C) Another term for latent heat D) Not relevant to system design Correct Answer: B) Heat that results in a measurable temperature change Rationale: Sensible heat is associated with a change in temperature, as opposed to latent heat where phase change occurs without temperature change.
Question 25: A refrigerant receiver is used in systems to: A) Store excess refrigerant when the system load changes B) Heat the refrigerant to a higher temperature C) Reject heat from the refrigerant
C) The mass of refrigerant in a system D) 1,200 BTU/hour Correct Answer: B) 12,000 BTU/hour of cooling capacity Rationale: One ton of refrigeration is equivalent to removing 12,000 BTU of heat per hour.
PART 3: SYSTEM TYPES & APPLICATIONS
Question 28: Direct Expansion (DX) systems are characterized by which primary feature? A) The use of chilled water loops to transfer heat B) The refrigerant evaporates directly in the system's evaporator coil C) The system always uses water-cooled condensers D) The system operates without a compressor Correct Answer: B) The refrigerant evaporates directly in the system's evaporator coil Rationale: In a DX system, the refrigerant evaporates (changes phase) directly inside the evaporator coil, absorbing heat from the air or another medium in direct contact with the coil.
Question 29: A split air conditioning system typically has:
A) Both evaporator and condenser housed in a single outdoor unit B) Evaporator (indoor unit) and condenser (outdoor unit) separated C) No ducts D) A single package on the rooftop Correct Answer: B) Evaporator (indoor unit) and condenser (outdoor unit) separated Rationale: A split system places the evaporator indoors and the condenser/compressor unit outdoors, "splitting" the components.
Question 30: Ductless mini-split systems differ from standard split systems because: A) They require separate ductwork for each room B) The condenser is indoors while the evaporator is outdoors C) They have individual air handlers in the space without using ductwork D) They cannot be used for residential applications Correct Answer: C) They have individual air handlers in the space without using ductwork Rationale: A ductless mini-split uses one or more indoor air handlers without needing extensive ductwork, making them ideal for specific zones or spaces.
Question 33: A chilled water system differs from a DX system because: A) It uses water as a secondary medium to absorb and transport heat B) It does not involve any heat exchange C) It cannot be used with multiple air handlers D) The refrigerant evaporates directly in the air stream Correct Answer: A) It uses water as a secondary medium to absorb and transport heat Rationale: In a chilled water system, refrigerant cools water in a chiller, and that chilled water is circulated to air handlers for space cooling.
Question 34: Which type of air conditioning system is commonly used in smaller residential spaces due to its high efficiency and easier installation? A) Central split system B) Window units C) Ductless mini-split D) Packaged rooftop unit Correct Answer: C) Ductless mini-split Rationale: Ductless mini-split systems are often used in smaller homes or rooms where installing ductwork would be complex or cost-prohibitive.
Question 35: A typical "walk-in cooler" is designed for which of the following functions? A) Storing non-perishable items B) Providing office ventilation C) Storing perishable products at stable, low temperatures D) Generating heat for commercial kitchens Correct Answer: C) Storing perishable products at stable, low temperatures Rationale: Walk-in coolers maintain a lower temperature to safely store perishable goods, such as meats, dairy, and produce.
Question 36: In commercial settings like retail stores and offices, air conditioning is important primarily because it: A) Increases the building's operating expenses B) Lowers employee productivity C) Helps maintain comfortable conditions for occupants and equipment D) Eliminates the need for energy audits Correct Answer: C) Helps maintain comfortable conditions for occupants and equipment
