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100+ Free NV C-21A Refrigeration Practice Questions

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2026 Statistics

Key Facts: NV C-21A Refrigeration Exam

50 Q

Official Exam Questions

PSI Nevada Contractor CIB updated 3/25/2026

70%

Passing Score

PSI Nevada Contractor CIB updated 3/25/2026

2 hours

Time Allowed

PSI Nevada Contractor CIB updated 3/25/2026

USD 95

PSI Exam Fee (one portion)

PSI Nevada Contractor CIB updated 3/25/2026

Open Book

Book Policy

PSI Nevada Contractor CIB updated 3/25/2026

Nevada C-21A Refrigeration Contractor Examination is the official NSCB/PSI open book exam: 50 questions, 70% (35 of 50 points), 2 hours, USD 95 (bulletin 270, updated 3/25/2026). Official delivery: English.

Sample NV C-21A Refrigeration Practice Questions

Try these sample questions to test your NV C-21A Refrigeration exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1NAC 624.380 limits Nevada C-21A refrigeration work to devices and machinery that control air temperatures in which range?
A.Below 50°F in refrigerators, refrigerated rooms, and insulated spaces
B.55°F to 75°F comfort cooling in occupied offices
C.Any temperature, including warm-air heating
D.Only ice-rink floors below 32°F
Explanation: NAC 624.380(3)(a) defines C-21A as construction and installation of devices, machinery, and units that control air temperatures below 50°F in refrigerators, refrigerated rooms, and insulated spaces, plus related insulation, ducts, blowers, registers, humidity and thermostatic controls. Comfort cooling above that line is C-21 or another classification, not C-21A. PSI bulletin 270 tests that low-temperature scope.
2In the vapor-compression cycle used on a walk-in freezer, which four components appear in order of refrigerant flow?
A.Compressor, condenser, metering device, evaporator
B.Evaporator, condenser, compressor, metering device
C.Condenser, evaporator, metering device, compressor
D.Metering device, compressor, evaporator, condenser
Explanation: Modern Refrigeration describes the standard cycle: the compressor raises vapor pressure and temperature; the condenser rejects heat so the refrigerant becomes liquid; the metering device drops pressure; the evaporator absorbs heat from the below-50°F box. That order is the same on a cooler, freezer, or process chiller.
3What is the evaporator's job in a 0°F walk-in freezer?
A.Absorb heat from the box air so the refrigerant vaporizes
B.Reject heat to outdoor air and condense the refrigerant
C.Raise refrigerant pressure without changing enthalpy
D.Store unused liquid refrigerant for winter head pressure
Explanation: In the freezer the evaporator is the low-side heat exchanger. Liquid refrigerant boils at a saturation temperature below box temperature and absorbs latent heat from the air. The compressor then removes that vapor. Condensing and storage happen elsewhere in the cycle.
4Where does a refrigeration system reject the heat it removed from a refrigerated room?
A.At the condenser (or condensing unit) to air or water
B.At the TXV bulb
C.At the crankcase heater
D.Only through the suction-line insulation
Explanation: The condenser is the high-side heat exchanger. Superheat, latent heat of condensing, and some subcooling are rejected to outdoor air, condenser water, or an evaporative condenser. UMC 2018 Chapter 11 treats condensers and cooling towers as part of that heat-rejection train.
5How is evaporator superheat calculated on a DX freezer coil?
A.Actual suction-vapor temperature minus saturation temperature at the suction pressure
B.Box temperature minus condenser saturation temperature
C.Liquid-line temperature minus outdoor dry-bulb
D.Discharge temperature minus suction temperature
Explanation: Superheat is how many degrees the suction vapor is warmer than saturation at the measured suction pressure. Convert pressure with the refrigerant P/T chart, then subtract that saturation temperature from a well-insulated probe at the evaporator outlet (or TXV bulb). Modern Refrigeration uses that value to set and diagnose TXVs.
6How is liquid-line subcooling calculated on an air-cooled condensing unit?
A.Saturation temperature at liquid-line (or discharge) pressure minus actual liquid-line temperature
B.Outdoor wet-bulb minus liquid-line temperature
C.Suction saturation minus box temperature
D.Discharge temperature minus condensing temperature only
Explanation: Subcooling is how many degrees the liquid is cooler than saturation at the measured high-side pressure. Convert the liquid-line or discharge pressure on the P/T chart, then subtract the actual liquid temperature leaving the condenser or receiver. Useful subcooling confirms a solid liquid column to the TXV.
7One ton of refrigeration is defined as which heat rate?
A.12,000 Btu/h (200 Btu/min)
B.1,000 Btu/h
C.3,412 Btu/h
D.288,000 Btu/h
Explanation: A refrigeration ton is the heat required to melt one ton of ice in 24 hours, which is 288,000 Btu/day, or 12,000 Btu/h, or 200 Btu/min. Nameplates, load calculations, and line-size tables for walk-ins are all stated in tons or Btu/h on that basis.
8Under ASHRAE 34 as used in UMC 2018 Table 1102.3, R-404A is classified in which safety group?
A.A1 (lower toxicity, no flame propagation)
B.B2L (higher toxicity, lower flammability)
C.A3 (lower toxicity, higher flammability)
D.B3 (higher toxicity, higher flammability)
Explanation: UMC 2018 Table 1102.3 lists R-404A as Group A1. The letter is toxicity (A lower, B higher) and the number is flammability (1 none, 2L lower, 2 flammable, 3 higher). R-404A remains the common low-temperature HFC on existing walk-ins and must be treated as an A1 refrigerant for occupancy and machinery-room triggers.
9UMC 2018 classifies a refrigeration system as high-probability when which condition is true?
A.A leak from a failed connection, seal, or component could enter an occupied space
B.The compressor nameplate exceeds 5 horsepower
C.The refrigerant is any Group A1 fluid
D.The condenser is located outdoors
Explanation: UMC 2018 1104.1 defines a high-probability system as one whose design or component locations allow leaked refrigerant to enter a normally occupied area. A DX evaporator in a work room is high-probability. A brine or glycol secondary loop that keeps the refrigerant circuit isolated is low-probability (1104.2) and is treated differently in Table 1104.1 occupancy rules.
10In the ASHRAE 34 / UMC 2018 refrigerant safety-group letter, what does Group B indicate?
A.Higher toxicity than Group A
B.No flame propagation
C.Lower flammability than Group A
D.The refrigerant is always ammonia
Explanation: The letter is toxicity: A is lower toxicity and B is higher toxicity, based on occupational exposure limits. The numeral is a separate flammability ranking. Ammonia is B2L, but other B refrigerants exist (for example R-123 is B1). UMC 2018 Table 1102.3 and Chapter 11 occupancy limits use both the letter and the number.

About the NV C-21A Refrigeration Exam

The Nevada C-21A Refrigeration Contractor Examination is the official Nevada State Contractors Board trade examination administered by PSI Services LLC. The official exam has 50 scored questions. Passing is 70% (35 of 50 points) in 2 hours. The examination is open book. Uniform Mechanical Code, 2018 (allowed in center). PSI lists USD 95 for one examination portion and USD 140 if taken with CMS; otherwise USD 95 per trade exam (Candidate Information Bulletin 270, updated 3/25/2026). NSCB requires a separate CMS examination for most new applicants, plus a USD 300 application fee and a USD 600 biennial license fee. This English-language MCQ bank is a study aid, not an official PSI form. It does not replace required trade experience, board approval, fingerprints, bonding, or the official examination.

Assessment

Open Book computer-based multiple-choice. Uniform Mechanical Code, 2018 (allowed in center)

Time Limit

2 hours

Passing Score

70% (35 of 50 points)

Exam Fee

USD 95 (PSI Services LLC (for the Nevada State Contractors Board))

NV C-21A Refrigeration Exam Content Outline

34%

Refrigeration and Refrigerants

Refrigeration and Refrigerants (17 items)

16%

Piping and Tubing

Piping and Tubing (8 items)

8%

Condensers and Cooling Towers

Condensers and Cooling Towers (4 items)

14%

Controls, Valves and Wiring

Controls, Valves and Wiring (7 items)

4%

Walk-ins/Box Construction

Walk-ins/Box Construction (2 items)

4%

Ducts and Ventilation

Ducts and Ventilation (2 items)

6%

Test and Inspection

Test and Inspection (3 items)

6%

Gas

Gas (3 items)

8%

Safety

Safety (4 items)

How to Pass the NV C-21A Refrigeration Exam

What You Need to Know

  • Passing score: 70% (35 of 50 points)
  • Assessment: Open Book computer-based multiple-choice. Uniform Mechanical Code, 2018 (allowed in center)
  • Time limit: 2 hours
  • Exam fee: USD 95

Keys to Passing

  • Work through all 100 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

NV C-21A Refrigeration Study Tips from Top Performers

1Distribute study time to the official bulletin 270 content outline (updated 3/25/2026)
2Use only the PSI-listed references; temporary tabs such as Post-it notes are prohibited
3Confirm NSCB experience documentation before scheduling with PSI
4This bank is an English-language MCQ study aid, not an official PSI form

Frequently Asked Questions

How many questions are on the Nevada C-21A Refrigeration Contractor Examination?

The official PSI examination has 50 scored questions. Passing is 70% (35 of 50 points) within 2 hours (Candidate Information Bulletin 270, updated 3/25/2026).

How much does the NV C-21A exam cost?

PSI lists USD 95 for one examination portion. Two portions cost USD 140 only if the second portion is CMS. NSCB charges a separate USD 300 application fee and USD 600 biennial license fee.

Is the NV C-21A exam open book?

Yes. PSI lists this examination as open book. Uniform Mechanical Code, 2018 (allowed in center)

Do I still need the CMS examination?

CMS is the required Nevada business-and-law examination. Most new applicants must pass CMS and a trade examination for the requested classification. In most cases you will not retake an exam if you have actively served as a qualified employee in the same classification within the last four years.