Free practice questions for Nevada's C-21 Refrigeration and Air Conditioning trade exam — the PSI test behind the NSCB's HVAC and refrigeration license — with a written explanation on every answer, in English, Spanish, and Russian.
8 questions, about 4 minutes. No account needed — pick an answer to see whether it's right and read the explanation, the same explanations you get on every question in the full course.
Practice across the full question bank.
Understand why the correct answer works — not just which letter is right.
Spend more time on the questions you miss.
Practice under exam-style time pressure before exam day.
Every question tells you why the correct answer is correct and defines the terms it uses — so you learn the rule, not just the answer.
Questions are written from scratch against the official codes and agency publications for this exam — never copied from the real exam.
Every question and explanation is fully translated, with the English exam term kept alongside — not a shallow machine translation.
LICENA is a practice tool, not a school. We don't promise a pass — we help you understand the material and walk in prepared.
The full Nevada C-21 course is 500 questions across 5 blocks mapped to PSI's own 22 subject areas — Fuel Systems 10, Refrigerants and Refrigeration 7, Piping 6, Load Calculations 6, Ducts 6, Chimneys/Flues/Vents 5, Controls 5, A/C and Heat Pump Equipment 4, Furnaces and Heaters 4, Solar 4, Safety 4, Hangers and Supports 3, Testing/Adjusting/Balancing 3, Heating and Cooling Principles 3, Chillers 3, Ventilation and Exhausts 3, Combustion Air 2, Hydronics 2, Evaporative Cooling 2, Insulation 1, Machine Room 1, Sound/Vibration/Seismic Control 1 — written to the exam's own references plus 40 CFR 82, 29 CFR 1926 and Nevada law.
Exam structure, topics, study areas and official resources.
The C-21 Refrigeration and Air Conditioning exam is the trade half of a Nevada HVAC license; the Contractor Management Survey (CMS) is the other half, and every NSCB applicant takes it. PSI's Nevada bulletin sets the C-21 format: 85 questions, a minimum passing score of 60, 3 hours, open book with the 2018 Uniform Mechanical Code and NFPA 54. Practice it in the free sample above: no sign-up, with a written explanation on every question.
The Nevada State Contractors Board requires every applicant, in every classification, to pass the Contractor Management Survey — the business-and-law exam — in addition to the trade exam. PSI's Nevada bulletin gives the CMS 60 questions, a minimum passing score of 45 and 2 hours; the C-21 Refrigeration and Air Conditioning trade exam gets 85 questions, a minimum passing score of 60 and 3 hours. One examination portion costs $95 and two portions $140. A candidate who tests unsuccessfully waits 2 weeks before retaking each portion, and a third failure voids the application — you then re-apply directly with the Board.
C-21 is open book, and the allowed list is exactly two references: the Uniform Mechanical Code, 2018 edition (IAPMO), and NFPA 54, the National Fuel Gas Code, 2012. Nothing else comes in — no manufacturer manuals, no ACCA manuals, no psychrometric charts of your own, no additional papers loose or attached. You may highlight, underline and index the books before the session but never write in them; only permanent tabs are allowed and Post-It notes must be removed. And for code questions the exam is based only on the edition listed, so a newer UMC is the wrong book. Given that Fuel Systems alone is ten of the eighty-five questions, tabbing NFPA 54 properly is worth an evening of your time.
PSI publishes 22 areas summing to 85 questions. The heavy end is Fuel Systems 10, Refrigerants and Refrigeration 7, then Piping 6, Load Calculations 6 and Ducts 6, followed by Chimneys, Flues and Vents 5 and Controls 5. Then come A/C and Heat Pump Equipment 4, Furnaces and Heaters 4, Solar 4 and Safety 4; Hangers and Supports, Testing/Adjusting/Balancing, Heating and Cooling Principles, Chillers and Ventilation and Exhausts at 3 each; Combustion Air, Hydronics and Evaporative Cooling at 2; and Insulation, Machine Room and Sound/Vibration/Seismic Control at 1. Read it as a plan: fuel gas, venting and combustion air together are about a fifth of the exam, and the calculation areas — loads, ducts, balancing — are another fifteen questions where a formula beats memory.
Refrigerant work carries federal law the state exam does not repeat but the job does. 40 CFR part 82 subpart F is the one to know: the venting prohibition with no amount threshold (§ 82.154), proper evacuation and the 15-pound ceiling on system-dependent recovery equipment (§ 82.156), and the Section 608 technician types — Type I small appliances, Type II medium/high/very high pressure, Type III low pressure, Universal for all of them (§ 82.161). Brazing brings 29 CFR 1926 subpart J: valve protection caps in place, cylinders secured upright, and oxygen kept 20 feet from fuel-gas cylinders or behind a noncombustible barrier 5 feet high with a half-hour rating. And any trench for a condenser pad or line set puts you under NRS 455.110 — notice to the one-call center at least 2 working days and not more than 28 calendar days ahead, plus white-lining the area.
You test on a computer at a PSI center in Nevada and PSI forwards the result to the Board. The bulletin lists NV C-21b AC Contractor among the exams offered in English and Spanish; to switch you call PSI at (855) 205-5827 or email examschedule@psionline.com. Registration fees are not refundable or transferable and expire with your eligibility, and applicants submit fingerprints for a state and national criminal history record as part of licensure. Applications, classifications, monetary limits and bonds are Board territory and are covered by the CMS — see the Nevada CMS practice test.
The full LICENA Nevada C-21 course is 500 questions across five blocks mapped to PSI's 22 areas. At 30 questions a day that is about three weeks: one pass to find the gaps, a second pass on the areas you missed, then the timed final at 85 questions in 3 hours — a pace of just over two minutes per question, which is tighter than most candidates expect from an open-book exam. That pace is the argument for practicing lookups rather than memorizing: tab your UMC and NFPA 54 early and use the same tabs every study session. Drill the sensible-heat and airflow arithmetic on paper. If you also hold or want EPA certification, the free EPA 608 practice test covers the refrigerant rules in more depth.
Try the full bank free for 3 days — no card needed. Then $9.99 for your first month and $19.99/month after that if you decide to continue, cancel anytime. A school sells a full prepaid package; this is a question bank you can stop at any time — and you study on your phone, in your language, whenever you have a few minutes.
Continue Nevada C-21 practice The free sample above stays free. Creating an account is free — no card needed.LICENA gives you practice questions to study with. We are not an accredited school and we do not guarantee that you will pass any exam.
LICENA provides online practice only. Registration, testing and licensing are handled by the Nevada State Contractors Board (NSCB) and PSI — not by LICENA. LICENA is not affiliated with the NSCB or PSI.