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Oklahoma Refrigeration Journeyman — Practice Exam Guide

What This Practice Exam Covers

The Oklahoma Refrigeration Journeyman licensing exam consists of 60 questions answered within 150 minutes. The passing score is 70%, meaning you must answer at least 42 questions correctly.

This practice exam is available in two forms:

• Free practice exam: 10 questions per attempt, drawn from a limited pool. You can retake it as many times as you like — it costs nothing and gives you a genuine feel for question style, phrasing, and difficulty before you commit to serious preparation.
• Full practice exam (paid): Mirrors the real exam exactly — 60 questions, 150-minute time limit. Questions are pulled from a pool of 366+ items, so every attempt produces a unique exam with no duplicate sets. Coverage maps directly to the six official topic areas and their exact item counts, giving you the most realistic preparation available.

Start with the free exam to calibrate where you stand, then use the full exam for timed, exam-realistic repetition.

What You'll Be Tested On

Electrical Knowledge and Controls — 15 items

This is the heaviest-weighted topic on the exam. Expect questions that require you to read both pictorial and ladder diagrams and trace circuit logic — not just identify symbols, but follow a circuit path to find an open or short. You must apply Ohm's law (V = IR), Watt's law (P = IE), and power factor calculations (PF = true power ÷ apparent power) with actual numbers. Inductive reactance and its effect on power loss are tested, so understand why a low power factor increases line current.

Motor questions cover single-phase types — split-phase, capacitor-start induction-run, capacitor-start capacitor-run, permanent split capacitor, and shaded-pole — as well as three-phase motors and how to reverse rotation by swapping two leads. Motor starting relays — current, potential, solid-state, and PTC types — are heavily tested, including how to check a current relay (coil resistance, vertical mounting orientation) versus a potential relay (open at rest, closed by back-EMF). Temperature and pressure motor controls require you to distinguish cut-in from cut-out, calculate range and differential settings, and know how high-pressure and low-pressure controls differ in function. Motor protection via fuses, circuit breakers, and bimetal/thermistor overloads rounds out this section.

Key references: Modern Refrigeration and Air Conditioning, Sections 13.1, 13.1.3, 15.2.1, 16.2, 16.3.4, 16.3.5, 16.4.3.

Refrigerants — 17 items

The largest topic by item count. You must know the ASHRAE numbering system for CFCs, HCFCs, HFCs, HFOs, hydrocarbons, and the inorganic series (R-700s). Environmental impact questions test ODP and GWP values, the Montreal Protocol phase-out schedule, and Clean Air Act Section 608 requirements.

Cylinder identification is frequently tested: color codes, DOT specifications, and safe handling rules. Pressure-temperature relationships require reading a P/T chart and knowing that a refrigerant at saturation has a fixed pressure for a given temperature.

EPA 608 content is substantial — know the recovery requirements for high-pressure refrigerants (0" Hg or 4" Hg depending on system size), medium-pressure refrigerants (0" Hg or 4" Hg), and low-pressure refrigerants (25 mm Hg absolute, as shown in the sample questions below). Know Type I, II, III, and Universal (Type IV) certification categories and which equipment each covers.

Piping — 3 items

Fewer questions, but don't skip this topic. Know ACR copper tubing types and how OD sizing differs from plumbing copper. Flare connections — both single and double flare procedures — are tested, including proper tube preparation (cutting square, reaming burrs). Brazing with nitrogen purge, appropriate filler metals, and flux selection are tested. Approved refrigerant piping materials standards round out this area.

Refrigeration Equipment and Components — 15 items

Equal in weight to Electrical. Compressor types — reciprocating, rotary, scroll, screw, and centrifugal — are tested on construction details, applications, and specific components (reed valves, piston rings, scroll wraps, inlet vanes). Open-drive versus hermetic configurations, including shaft seal materials and fully hermetic lubrication, are fair game.

Metering devices require functional knowledge: capillary tube sizing effects, TXV hunting and MSS adjustment, external versus internal equalization, and EEV operation. Evaporator and condenser construction — fin-and-tube, microchannel, shell-and-tube, and evaporative types — is tested for both form and function.

Refrigerant flow control questions cover solenoid valves, check valves, service valve positions (front-seated, back-seated, mid-position), hot-gas defrost versus hot-gas bypass valves, CPR and EPR valves, and relief valves. Liquid receivers, filter-driers (suction and liquid line), and sight glass/moisture indicator interpretation are also included.

Refrigeration Systems Operations — 5 items

These questions target fundamental theory. Know the four-component compression cycle and the role of each component. Understand sensible heat, latent heat, superheat, and subcooling — and be able to calculate each. The gas laws (Boyle's, Charles', Gay-Lussac's, and the combined gas law) are tested with actual values. High-side versus low-side pressure relationships and saturated vapor conditions on a P/T chart tie directly into practical troubleshooting.

Safety — 5 items

Expect questions grounded in OSHA 29 CFR 1926 regulations. PPE selection, lockout/tagout procedures, fire extinguisher classes and the PASS method, SDS sheet sections, and compressed gas cylinder storage (per 29 CFR 1926, §1926.350(a)(10) and §1926.350(g)(3)) are all tested. Know the difference between extinguisher types for electrical versus chemical fires.

Worked Sample Questions

Question 1 — Refrigerants

What evacuation level is required for low-pressure refrigerants (R-123)?
- A. 10" Hg
- B. 15" Hg
- C. 20" Hg
- D. 25 mm Hg absolute

Correct Answer: D — 25 mm Hg absolute

EPA Section 608 sets a uniquely stringent recovery requirement for low-pressure refrigerants like R-123. Unlike high- and medium-pressure refrigerants measured in inches of mercury vacuum, the standard for low-pressure systems is expressed in absolute pressure: 25 mm Hg absolute. This is the deepest recovery requirement in the 608 rules, reflecting that low-pressure refrigerants operate below atmospheric pressure and require different recovery techniques. Confusing the unit (absolute vs. gauge) or the value with high-pressure requirements is a common error.

Reference: EPA Section 608, Type III Recovery Techniques.

Question 2 — Electrical Knowledge and Controls

Compressor won't start, high voltage present, weak capacitor. What is the correct repair?
- A. Replace fan motor
- B. Recharge refrigerant
- C. Replace start capacitor
- D. Adjust thermostat anticipator

Correct Answer: C — Replace start capacitor

When supply voltage is confirmed good but the compressor fails to start, the capacitor is the prime suspect. A start capacitor provides the phase shift needed to generate starting torque. A weak or failed capacitor cannot deliver sufficient boost, leaving the motor locked on the start winding — causing it to hum, trip on overload, or fail to turn at all. Recharging refrigerant or adjusting the thermostat has no bearing on this symptom. Replace the capacitor and verify starting performance.

Reference: Modern Refrigeration and Air Conditioning, Section 15.2.1 (Capacitor-Start, Induction-Run Motors).

Question 3 — Refrigeration Equipment and Components

You are troubleshooting a rotary compressor on a PTAC unit. You suspect refrigerant is flowing backward during the Off cycle. What component prevents high-pressure vapor and oil from flowing back into the evaporator?
- A. A check valve in the suction line or discharge
- B. A crankcase heater
- C. An oil separator in the discharge line
- D. A thermal expansion valve

Correct Answer: A — A check valve in the suction line or discharge

Rotary compressors lack the reed valves that block backflow in reciprocating compressors. During the Off cycle, high-pressure discharge vapor can migrate backward through the compressor and into the suction/evaporator side. A check valve installed in the discharge — or a suction-line check valve — prevents this backflow of refrigerant and compressor oil. A crankcase heater addresses liquid refrigerant migration, not vapor backflow. A TXV controls refrigerant metering, not reverse flow protection.

Reference: Modern Refrigeration and Air Conditioning, Chapter 18, Section 18.2.2 — Rotary Compressors (check valve).

How to Read Your Score

The passing threshold is 70% — 42 correct out of 60 questions.

Treat your first practice attempt as a diagnostic tool, not a final verdict. A first-attempt score tells you which of the six topic areas need work, not whether you'll pass the real exam. Use the topic-by-topic breakdown to identify your weakest areas rather than focusing only on your total.

Here's a practical interpretation:

• Below 60%: Significant gaps exist — prioritize the heavy topics (Electrical and Refrigerants) immediately.
• 60–69%: You're close but not ready. One or two topic areas are pulling your score down; find them and drill there.
• 70–79%: Passing range on practice, but scoring near the cutoff means exam-day nerves and unfamiliar phrasing can tip you below. Keep studying.
• 80% and above: Strong preparation — reinforce weak subtopics and focus on timed exam conditions.

A score near 70% on practice typically means more work is needed, not that you're ready. The full practice exam's 366+ question pool ensures you're seeing material that genuinely varies from attempt to attempt, so a consistent 75%+ across multiple full attempts is a more reliable readiness signal than a single good score.

Where Candidates Lose Points

Electrical calculations with wrong units. Watt's law and power factor questions often present mixed units — confusing apparent power with true power, or misidentifying which value to plug into PF = W ÷ VA. Write out the formula before solving.

Refrigerant recovery levels. Candidates mix up the recovery standard for low-pressure refrigerants (25 mm Hg absolute) with high-pressure requirements. The unit and the scale are both different — this is a one-answer-only question with no partial credit.

Pressure control settings. Questions on cut-in, cut-out, range, and differential adjustments require knowing which direction each screw moves the set point. Confusing range with differential is one of the most common errors in the Electrical topic.

Compressor component identification. Reciprocating compressor questions test specific sub-components — Scotch yoke versus eccentric connecting rod, reed valve versus poppet valve, clearance volume effects. Candidates who studied compressors only at the system level miss these.

Refrigerant cylinder color codes and DOT regulations. These seem like memorization questions, but the exam asks them in applied contexts (e.g., identifying an overfilled cylinder by weight limit rules). Know the rules, not just the colors.

Time management on the heavy sections. Electrical (15 items) and Refrigerant Equipment (15 items) together represent half the exam. Candidates who spend too long on multi-step calculations in those sections run short on time for the easier Safety and Piping questions at the end.

Exam Quick Facts