Oklahoma - REFRIGERATION CONTRACTOR

Oklahoma Refrigeration Contractor License Exam: Complete 2026 Study Guide

You've put in the hours on the job. Now it's time to make it official. Passing the Oklahoma Refrigeration Contractor exam is what separates working in the trade from running your own licensed operation — and it opens the door to bigger commercial projects, better contracts, and the credibility clients expect. This guide breaks down exactly what's on the 80-question exam, what to study first, and how to walk in confident on test day. You can also get a head start right now with our free practice exam.

Exam Overview

The Oklahoma Refrigeration Contractor exam consists of 80 scored questions completed in 210 minutes (3.5 hours). You need to answer at least 56 questions correctly to pass — that's a 70% passing score.

The exam is computer-based and multiple-choice. Each question has four answer options, and you'll be selecting the single best answer. Three and a half hours is generous, but don't let that lull you into moving too slowly on the straightforward questions. You'll want time to review the ones that require calculation or diagram analysis.

The exam covers six topic areas ranging from electrical fundamentals and refrigerant regulations to piping procedures and system troubleshooting. Some sections pull heavily from code books and industry standards, so knowing your reference materials matters as much as hands-on experience.

Topics Covered on the Oklahoma Refrigeration Contractor Exam

Here's a breakdown of each topic area and how heavily it's weighted:

Electrical Knowledge and Controls — 20 questions

This is one of the largest sections. Expect questions on Ohm's Law, Watt's Law, series and parallel circuits, power factor, and the differences between single-phase and three-phase systems. Motor types — split-phase, CSIR, CSCR, PSC, and shaded-pole — are also covered, including how each starts and where it's typically used.

Refrigerants — 20 questions

Another heavily weighted section. This covers refrigerant classification (CFC, HCFC, HFC, HFO, HC, inorganic), environmental regulations under the Montreal Protocol and EPA Section 608, cylinder color codes, DOT regulations, and proper recovery/recycling/reclaiming procedures. Know the difference between ODP and GWP, and be clear on what technicians are legally required to do.

Refrigeration Equipment and Components — 20 questions

This section tests your knowledge of compressors (reciprocating, scroll, screw, centrifugal), metering devices (capillary tubes, TXVs, EEVs), evaporators, condensers, and control components like solenoid valves, check valves, and filter-driers. Understanding how each component functions within the full system is key.

Refrigeration Systems Operations — 10 questions

Expect questions on the refrigeration cycle, pressure-enthalpy diagrams, the effects of refrigerant undercharge or overcharge, and how noncondensables or moisture affect system performance. Heat load calculation and component sizing round out this section.

Piping — 5 questions

Covers ACR copper tubing types, cutting and bending, flared connections (single and double flare), soldering and brazing with proper filler metals and nitrogen purging, and swaged connections.

Safety — 5 questions

PPE selection, lockout/tagout (LOTO) procedures, fire extinguisher requirements, and refrigerant cylinder handling. This section is smaller, but the material is straightforward and worth getting right.

Sample Questions

Here are a few questions representative of what you'll encounter. See if you can work through them — then check how you do on our free practice exam.

Question 1 — Refrigeration Equipment and Components

You are servicing a commercial refrigeration system and suspect that oil circulation through the evaporator is reducing heat transfer efficiency. Why is oil in the evaporator particularly problematic in low-temperature installations?

• A) Oil freezes solid below 0°F and blocks the evaporator tubes
• B) Oil thickens at low temperatures and becomes difficult to move out of the evaporator
• C) Oil chemically reacts with the refrigerant at low temperatures
• D) Oil causes excessive frost buildup on the evaporator surface

This question tests your understanding of oil behavior in refrigerant circuits — a practical issue that shows up often in commercial low-temp work.

Question 2 — Piping

You are a contractor installing refrigerant piping in a commercial building. The piping runs through an area away from the equipment room. How frequently must identification labels be placed on the refrigerant piping, and what is the minimum lettering height?

• A) Every 20 feet with 1/2″ minimum lettering
• B) Every 10 feet with 1/4″ minimum lettering
• C) Every 30 feet with 3/4″ minimum lettering
• D) Every 50 feet with 1″ minimum lettering

Code-based piping identification question — this is the kind of detail that comes straight from the IMC.

Question 3 — Refrigeration Equipment and Components

You are reviewing the design of a reciprocating compressor's cylinder head for a commercial refrigeration application. In addition to sealing the top of the cylinder for compression, what other critical function does the cylinder head perform?

• A) It houses the crankshaft main bearings and oil pump
• B) It contains the piston rings and connecting rod bushings
• C) It serves as the primary heat sink for compressor cooling
• D) It provides vapor passages for refrigerant flow into and out of the compressor

Tests deeper knowledge of compressor construction — not just what the cylinder head does, but how it fits into the refrigerant flow path.

Question 4 — Electrical Knowledge and Controls

An in-line ammeter is connected in series with a circuit containing a light and a heating element in series. If one ammeter reads 2 A, what will the other ammeters in the series circuit read?

• A) 4 A, because current doubles at each load
• B) 1 A each, because current splits evenly
• C) 0 A, because current is divided among loads
• D) 2 A, because current is the same at every point in a series circuit

A direct application of series circuit fundamentals — the kind of electrical question that rewards knowing your basics cold.

Question 5 — Refrigerants

Although it is illegal to knowingly vent refrigerant into the atmosphere, under what circumstances does the EPA allow technicians to release small amounts of refrigerant?

• A) Only during system commissioning of new equipment
• B) During recovery, repair, purging, and charging operations
• C) Only when working with non-ozone-depleting refrigerants
• D) Only when the system contains less than 10 pounds of refrigerant

Section 608 compliance — this tests your knowledge of EPA regulations around refrigerant handling, which every licensed contractor needs to know.

Don't worry if you're not sure of all the answers yet. These questions are designed to make you think, and the full practice exam gives you detailed topic breakdowns so you know exactly where to focus.

What Types of Questions to Expect

Here's a topic-by-topic breakdown of the kinds of problems our practice bank covers — and the number of practice questions available in each area:

• Electrical Knowledge and Controls (70 practice questions): Ohm's Law and Watt's Law calculations, circuit analysis problems for series and parallel configurations, power factor and apparent-vs-true power, and motor identification questions covering split-phase, PSC, and three-phase systems.

• Refrigerants (93 practice questions): Refrigerant classification, ODP and GWP comparisons, Montreal Protocol requirements, Section 608 compliance scenarios, cylinder handling under DOT rules, and recovery/recycling/reclaiming procedure questions.

• Refrigeration Equipment and Components (94 practice questions): Compressor type identification and operating principles, metering device selection and troubleshooting (TXVs, EEVs, cap tubes), evaporator and condenser construction differences, defrost method selection, and control component functions.

• Refrigeration Systems Operations (57 practice questions): Refrigeration cycle phase analysis, pressure-enthalpy diagram reading, refrigerant charge diagnosis (undercharge vs. overcharge symptoms), noncondensable and moisture contamination effects, and heat load sizing concepts.

• Piping (25 practice questions): ACR tubing type selection (Type K vs. L, soft vs. hard-drawn), brazing and soldering procedure questions, flare connection specifications, nitrogen purging requirements, and pipe labeling code questions.

• Safety (24 practice questions): PPE selection for refrigerant and electrical hazards, LOTO procedure steps, fire extinguisher class requirements, compressed gas cylinder storage rules, and SDS interpretation.

That's 363 practice questions total across all six topic areas.

Required Study Materials

Three references are essential for this exam:

Modern Refrigeration and Air Conditioning, 20th Edition

This is the backbone of your technical preparation. It covers the refrigeration cycle, compressor types, metering devices, electrical controls, and refrigerants in depth — essentially the full scope of what the exam tests on the technical side. If you only buy one book, make it this one.

International Mechanical Code 2021

The IMC is the code foundation for piping requirements, refrigerant system installation standards, and equipment room specifications. That pipe labeling question above? Straight from the IMC. Keep a copy tabbed and know how to find answers quickly.

OSHA 29 CFR 1926

The OSHA construction standard covers the safety material tested in the exam's Safety section — PPE, lockout/tagout, fire protection, and hazard communication. It's dense reading, but the exam questions tend to be specific, so knowing your OSHA requirements is worth the time.

Study Tips for the Oklahoma Refrigeration Contractor Exam

Start with the high-weight topics. Electrical Knowledge and Controls, Refrigerants, and Refrigeration Equipment and Components each carry 20 questions — that's 75% of the exam between just three topic areas. Get those right and you have a strong foundation for passing.

Don't skip refrigerant regulations. Section 608, ODP, GWP, and proper recovery procedures show up consistently. These questions are very learnable — they're mostly about knowing the rules, not doing complex calculations.

Practice reading pressure-enthalpy diagrams. Even if you're comfortable with them on the job, the exam tests whether you can interpret them correctly under timed conditions.

Know your motor types. Split-phase, CSIR, CSCR, PSC, and shaded-pole motors each have distinct starting characteristics. These questions reward memorization and understanding of where each motor is used.

Use the IMC as a reference, not just reading material. Practice looking things up quickly — the exam doesn't give you unlimited time to search through a code book, so know where the key sections are.

Take timed practice sessions. You have 210 minutes for 80 questions — that's about 2.5 minutes per question. Plenty of time, but only if you're not getting stuck. Practice under realistic conditions.

FAQs

How many questions are on the Oklahoma Refrigeration Contractor exam?
The exam has 80 scored questions. You have 210 minutes to complete it.

What is the passing score?
You need to answer 56 out of 80 questions correctly — a 70% passing score.

What reference materials are allowed during the exam?
Check with your testing provider for the current approved reference list. The IMC and OSHA standards are commonly referenced for mechanical contractor exams, but confirm what's allowed before your test date.

How do I prepare for the electrical section if I'm stronger on the refrigeration side?
Focus on the fundamentals: Ohm's Law, Watt's Law, and series vs. parallel circuit rules. These principles underpin most of the electrical questions. Work through calculation problems until the formulas feel automatic.

Is the exam hard to pass?
With solid preparation, it's very achievable. The 70% passing threshold means you can miss 24 questions and still pass. Focus your energy on the three 20-question topics, build your code knowledge, and use practice exams to identify weak spots before test day.

Conclusion

The Oklahoma Refrigeration Contractor exam is a real test of both hands-on knowledge and code familiarity — but it's absolutely passable with the right preparation. Get your reference books, work through the topic areas systematically starting with the highest-weight sections, and use practice questions to build confidence and catch gaps early.

Start today: try our free practice exam to get a feel for the question style and see where you stand. When you're ready to go deeper, the full practice exam gives you 363 questions across all six topic areas with detailed score breakdowns by topic. Good luck — you've got this.