Oklahoma HVACR Contractor, Limited

Oklahoma HVACR Contractor, Limited Exam: Complete 2026 Study Guide

Picture this: you've been doing HVAC work for years, and the only thing standing between you and your Oklahoma contractor license is one 80-question test. That's both good news and a little nerve-wracking. The Oklahoma HVACR contractor limited exam covers everything from refrigeration cycles to gas venting, and passing it opens the door to legally bidding and pulling permits as a licensed contractor in the state. This guide breaks down exactly what's on the test, what books to bring, and how to use your time wisely on exam day. You can also start building your confidence right now with a free practice exam.

Oklahoma HVACR Contractor, Limited Exam Overview

The Oklahoma HVAC contractor license test is administered by PSI and is overseen by the Oklahoma Construction Industries Board (CIB). Here are the key numbers:

• Questions: 80 scored questions
• Time limit: 210 minutes (3.5 hours)
• Passing score: 70%, which means you need at least 56 correct answers out of 80
• Format: Multiple-choice
• Open book: Yes — you bring your own approved references

This exam is open book, which is a big deal. You're not expected to have every gas pipe sizing table memorized. What you are expected to do is find the right answer quickly and apply code and technical knowledge accurately. Think of it as an open-book test where the clock is the main challenge, not your memory.

You can review the full candidate information at the official exam bulletin.

Topics Covered on the Oklahoma HVACR Contractor, Limited Exam

The exam spans six topic areas. Here's how they break down by number of questions, from highest to lowest weight:

Refrigeration and Air Conditioning Systems — 20 questions

The largest single topic. Covers the compression refrigeration cycle, refrigerant classification and EPA regulations under the Clean Air Act, handling equipment (cylinders, gauge manifolds, service valves), recovery and charging procedures, and metering devices like TXVs, capillary tubes, and EEVs.

Electrical Knowledge and Controls — 15 questions

Circuit diagrams, Ohm's law and Watt's law calculations, AC motor types and starting methods, motor starting relays (current, potential, solid-state, PTC), and pressure/temperature controls with cut-in and cut-out adjustments.

Air Distribution Systems — 15 questions

Duct types (radial, extended plenum, reducing trunk, perimeter loop, SDHV), ACCA Manual D sizing procedures, registers and grilles, damper types and automatic controls, and duct insulation and sealing per IMC Chapter 6.

Heating Systems — 15 questions

Gas-fired burners, ignition systems, combustion controls, oil-fired burner components and combustion efficiency, hydronic heating (boilers, circulating pumps, expansion tanks), heat pump operation, and electric resistance heating.

Natural Gas — 12 questions

Gas piping materials (steel, copper, CSST, PE), sizing methods and capacity tables, pressure testing and leak checks, combustion air requirements, and venting system types by appliance category.

Safety — 3 questions

Lockout/tagout (LOTO), fire extinguisher use (P.A.S.S.), refrigerant cylinder safety, PPE selection, and GHS/HCS labeling and safety data sheets.

Refrigeration, Electrical, Air Distribution, and Heating together account for 65 of the 80 questions — that's where your study time should be concentrated.

Sample Exam Questions

Here's a look at the style and difficulty of questions you'll face on the Oklahoma mechanical contractor exam. See if you can reason through them — but don't worry if you're unsure. That's exactly what practice is for.

Question 1 — Heating Systems (Hard)

When measuring combustion efficiency on a natural gas furnace, what is the acceptable carbon dioxide (CO₂) content by volume in the flue gas after accounting for excess air dilution?
- A) 8.9%
- B) 13.9%
- C) 7.6%
- D) 11.9%

Question 2 — Air Distribution Systems (Hard)

When supply-side duct leakage exceeds return-side duct leakage in a system running through unconditioned space, what pressure condition results in the conditioned space?
- A) Negative pressure with increased infiltration
- B) Positive pressure with increased infiltration
- C) Neutral pressure with no infiltration change
- D) Positive pressure with increased exfiltration

Question 3 — Heating Systems (Medium)

A high-temperature safety cutoff in an electric furnace uses a fusible link. Unlike a bimetal disc safety cutoff, what must be done after a fusible link opens?
- A) It must be replaced entirely
- B) It must be manually reset
- C) It must be recalibrated by the manufacturer
- D) It resets automatically on cool-down

Question 4 — Air Distribution Systems (Medium)

When duct load factors are generated using Manual J default models, the default supply-side and return-side surface areas are compatible with which two duct system geometries?
- A) Reducing trunk and perimeter loop
- B) Trunk-and-branch and perimeter loop
- C) Radial and extended plenum
- D) Primary-secondary and radial

Question 5 — Refrigeration and Air Conditioning Systems (Medium)

You are servicing a commercial refrigeration unit and need to recover the refrigerant. Your recovery machine was manufactured in 2020. What certification requirement must this machine meet?
- A) It must carry a UL listing for use with flammable refrigerants
- B) It must be certified by an EPA-approved testing organization to achieve required vacuum levels
- C) It must be certified by ASHRAE to meet Standard 15 requirements
- D) It must be certified by the DOT for safe refrigerant transport

Not sure on a few of those? That's normal at this stage. Start with our free practice exam to get a feel for how questions are structured before moving to full timed simulation.

What Types of Questions to Expect

Here's a topic-by-topic look at the kinds of problems the exam tests — and how many practice questions we've built for each area:

• Refrigeration and Air Conditioning Systems (157 practice questions): Expect questions on refrigerant recovery procedures, EPA certification requirements, identifying metering device behavior at different load conditions, refrigerant properties, and gauge manifold readings during evacuation and charging.

• Electrical Knowledge and Controls (113 practice questions): Ohm's law and Watt's law calculations, reading pictorial and ladder diagrams, identifying motor starting relay types, and adjusting pressure and temperature controls with specific cut-in/cut-out values.

• Air Distribution Systems (98 practice questions): Duct sizing using Manual D methods, identifying the right duct geometry for a given application, airflow characteristics of different register and diffuser types, damper functions, and duct sealing and insulation requirements from the IMC.

• Heating Systems (82 practice questions): Combustion efficiency testing for both gas and oil systems, heat pump reversing valve operation, hydronic system component identification, electric heating safety controls (including fusible links and bimetal discs), and burner and ignition system troubleshooting.

• Natural Gas (56 practice questions): Gas pipe sizing using longest-length and branch-length methods, reading capacity tables, pressure testing procedures, combustion air calculations, and selecting venting system types by appliance category.

• Safety (14 practice questions): LOTO procedures, P.A.S.S. fire extinguisher method, refrigerant cylinder handling, PPE requirements, and SDS/GHS label interpretation.

In total, we offer 520 practice questions across all six topics for the OK HVACR limited practice exam.

Study Materials for the Oklahoma HVACR Contractor, Limited Exam

This exam is open book, and these are the approved references. Buy them, tab them, and know them well:

• Modern Refrigeration and Air Conditioning (20th Edition) — The core refrigeration reference. Covers the compression cycle, refrigerant handling, metering devices, and more. The exam's largest topic pulls heavily from this book.

• Manual J — Residential Load Calculation (8th Full Edition) — Required for Air Distribution questions. Know how duct load factors and surface area defaults work.

• Mathematics for Plumbers and Pipefitters (8th Edition) — Covers the arithmetic and applied math skills that come up in pipe sizing, Ohm's law problems, and gas calculations.

• 2018 International Mechanical Code (IMC) — Required for duct construction, insulation, sealing, and ventilation requirements. Tab Chapter 6 heavily.

• 2018 International Fuel Gas Code (IFGC) — Your go-to for gas piping materials, sizing tables, combustion air, and venting. Essential for the Natural Gas and Heating Systems topics.

• ACCA Ductulator (Duct Slide Rule) — Optional but very useful. This tool speeds up duct sizing on test day significantly. Practice with it before the exam so you're not fumbling with it under time pressure.

Study Tips for the Oklahoma HVACR Contractor, Limited Exam

Because the exam is open book, speed of lookup is the real skill — not memorization.

• Tab your code books by chapter. Put permanent tabs on the gas pipe sizing tables in the IFGC, the combustion air section, and the vent tables. Natural Gas and Heating Systems together are 27 of the 80 questions, and those topics live in those two codes.

• Know your refrigeration cold. Refrigeration and Air Conditioning Systems is 20 questions — the biggest slice of the exam. Read Modern Refrigeration and Air Conditioning on the refrigeration cycle, compressor types, metering devices, and superheat/subcooling checks until those concepts are second nature.

• Work Ohm's law problems every day. Electrical Knowledge and Controls is 15 questions. A few minutes of daily calculation practice on series/parallel circuits and motor starting relays adds up fast.

• Get comfortable with your Ductulator. Air Distribution is another 15 questions. Use the Ductulator for duct sizing practice until the process feels automatic.

• On test day, answer lookup questions first. Flag the calculation-heavy questions and come back to them. Grabbing the code-reference points quickly frees up more time for the problems that require real thinking.

• Bring a silent, non-programmable calculator. You'll need it for electrical and gas calculations.

Note: You may highlight and underline in your references and use permanent tabs before the exam, but you may not write notes in the books before or during the session. Temporary tabs like Post-It notes are not allowed.

Frequently Asked Questions

How many questions are on the Oklahoma HVACR Contractor, Limited exam and how long do I have?
The exam has 80 scored questions and you are given 210 minutes to complete it. That works out to just over 2.5 minutes per question — enough time if you move steadily and don't get stuck on any single item.

What is the passing score?
You need to answer 70% of questions correctly, which means getting at least 56 of the 80 scored questions right.

How much does the exam cost?
The exam fee is $92 per examination portion. This fee is non-refundable and non-transferable, whether you're testing for the first time or retesting after a failed attempt.

How do I register?
Once the Oklahoma Construction Industries Board approves your application, you can schedule your exam through the exam registration page or by calling PSI at (855) 834-8750. You'll need your OK Con ID number from the Board to create your PSI account.

What happens if I fail?
After a first failure, you must wait 30 days before retesting. A second or subsequent failure means a 90-day wait.

Does my exam eligibility expire?
No. According to the exam bulletin, there is no expiration on your eligibility once you've been approved.

Is the exam open book?
Yes. You bring your own approved reference materials to the testing center. See the list above for what's permitted.

Can I write in my books?
You may highlight, underline, and use permanent tabs. You may not write in the books before or during the exam, and temporary tabs (like Post-It notes) are not permitted.

What ID do I need to bring?
One valid, non-expired, government-issued photo ID that also bears your signature — a driver's license, state ID, U.S. passport, military ID, alien registration card, or Canadian government-issued ID. The name must match your registration exactly.

Ready to Start Preparing?

Passing the Oklahoma HVACR contractor limited exam is completely achievable with the right materials and a focused study plan. You know the topics, you know the weights, and you know the books to bring. The next step is practice.

Start free — our free practice exam gives you 10 questions drawn from real exam content with no account or payment required. It's a quick way to see where you stand. When you're ready to go deeper, the full practice exam matches the real test format (80 questions, 210 minutes) and draws from a pool of 520 questions across all six topics, with a detailed score breakdown so you can see exactly where to focus next.

Check the state licensing website for application requirements, get your books ordered, and start tabbing. You've got this.