C-38 Refrigeration exam questions, with answers
10 practice questions for the CSLB Refrigeration trade exam, each with the answer, a plain explanation and the source it rests on.
These are not real exam questions. CSLB does not release its test questions or answer keys, and nobody else has them. We write our own questions from the C-38 outline and the codes, standards and references CSLB lists for the exam. Each answer names its source so you can check it.
The C-38 exam has 5 sections. The questions below are grouped by section, with the share of the exam each one carries. Read the question, pick an answer, then open “Show the answer”. The other questions of the free test, scored section by section, are in the free 25-question C-38 test.
Planning and Estimating · 18% of the exam
Planning refrigeration projects; estimating refrigeration projects.
1. A brewery asks your C-38 company to install a process chiller that will cool a glycol loop to 28°F for its fermentation tanks. No refrigerated room is part of the job. Under 16 CCR 832.38, does this work fall within the C-38 Refrigeration classification?
- No; cooling a liquid below 32°F falls outside the classification
- Yes; the class covers control of liquid temperatures below 50°F
- No; the class covers only air temperatures in refrigerated rooms
- Yes, but only when the chiller sits inside an insulated room
Show the answer
Answer: B. 16 CCR 832.38 defines C-38 work as refrigeration and related equipment for the control of air, liquid and/or gas temperatures below 50°F (10°C). A glycol loop held at 28°F is a liquid below 50°F, so the chiller job fits. The classification is not limited to air or to refrigerated rooms, and it sets no lower temperature limit.
2. A restaurant owner wants the 3-hp condensing unit for a new walk-in set inside the building's required exit stairway enclosure, the only spare indoor space. Under the 2025 California Mechanical Code 1105.6, may the unit go there?
- No; refrigeration equipment may not sit in a required exit enclosure
- Yes, if its access ports get locking, tamper-resistant caps
- Yes, if the compressor sits at least 10 ft from the enclosure's exit door
- Yes; the location limits in 1105.6 apply only to compressors over 5 hp
Show the answer
Answer: A. 2025 California Mechanical Code 1105.6 lists prohibited locations: refrigeration equipment may not be placed in a required exit enclosure. The 5-hp and 10-ft figures in the same section are a separate limit on larger compressors near exit openings; they do not make an exit enclosure acceptable. Locking caps (1105.11) protect outdoor access ports and have nothing to do with exits.
Refrigeration System Installation · 26% of the exam
Job site preparation; installing refrigeration equipment; starting up refrigeration systems; installing specialty refrigeration systems.
3. A grocery's new semi-hermetic condensing unit will be set in an indoor equipment room, and the owner wants shelving along the route to it. Under the 2025 California Mechanical Code 1105.3, what clear passage must stay open to the compressor?
- At least 36 in wide and 72 in high
- At least 30 in wide and 80 in high
- At least 30 in wide and 30 in high
- At least 36 in wide and 80 in high
Show the answer
Answer: D. 2025 California Mechanical Code 1105.3 requires an unobstructed access passage at least 36 in wide and 80 in high to compressors and their valves. The 30 x 30 x 30 in clear space is allowed only for smaller serviceable parts such as filters, fan motors and stop valves, not as the passage to the compressor.
4. You have just finished charging a new walk-in cooler system whose condensing unit has a crankcase heater. Copeland's liquid refrigerant bulletin and Heatcraft's condensing unit manual give the same advice for the first start. What is it?
- Energize the crankcase heater several hours before starting
- Leave the crankcase heater off until the box reaches set point
- Energize the crankcase heater only after a 30-minute first run
- Start the compressor at once so the oil warms up while it runs
Show the answer
Answer: A. Right after charging, most of the refrigerant and all of the oil may sit in the compressor, and a cold start can slug liquid and damage it. Copeland's bulletin AE22-1182 says the heater should be energized for several hours (at least four) before start-up, and Heatcraft's manual says to turn it on several hours before start-up. Starting at once or delaying the heater gives the refrigerant no time to leave the oil.
Refrigeration System Repair · 22% of the exam
Troubleshooting refrigeration systems; troubleshooting electrical problems; repairing refrigeration systems.
5. A medium-temperature case's R-134a condensing unit is running warm. At the condenser outlet the liquid line pressure is 146 psig, which an R-134a P-T chart lists as 110°F, and the liquid line there reads 98°F. Outdoor air at the condenser is 85°F. What is the subcooling?
- 12°F
- 13°F
- 25°F
- 48°F
Show the answer
Answer: A. Subcooling is the saturated condensing temperature minus the actual liquid line temperature: 110°F - 98°F = 12°F. 13°F compares the liquid line with the outdoor air, 25°F is the condenser's temperature difference over ambient (110 - 85), and 48°F subtracts the liquid temperature from the gauge reading in psig as if it were a temperature.
Source: Danfoss TXV fitters notes: subcooling definition (P-T value given in the question)
6. Power to a reach-in's condensing unit is off and locked out, and you are about to pull its start capacitor to test it. What do Tecumseh's service handbook and an ACHR News component-check article both say to do first?
- Wait 60 seconds, since locking out the power drains the charge
- Bump the compressor for 1 second so the start winding drains it
- Measure its capacitance while it is still wired in the circuit
- Discharge it through a 20,000-ohm resistor across its terminals
Show the answer
Answer: D. A capacitor can hold a charge after the power is off. Tecumseh's handbook says to discharge it with a 20,000-ohm resistor before removing it, to avoid electric shock and damage to meters, and ACHR News gives the same step with a 2-watt, 20,000-ohm resistor. Testing it in the circuit, bumping the compressor, or simply waiting do not reliably remove the stored charge.
Refrigeration System Maintenance · 18% of the exam
Maintaining refrigeration systems; documenting code compliance.
7. On each monthly PM visit, your technician records the liquid level in the receiver of a supermarket's compressor rack. According to EPA's GreenChill leak prevention checklist, what can a drop from the previous reading indicate?
- A compressor oil level that needs topping off
- Condenser fans cycling on and off too often
- Defrost heaters staying on for too long
- A refrigerant leak somewhere in the system
Show the answer
Answer: D. EPA's GreenChill leak prevention checklist says to identify and log the receiver refrigerant level of each rack, because a drop from a previous reading may indicate a leak in the system. Logging the level lets a leak be found while it is still small. Fan cycling, oil level and defrost heaters are checked in other ways.
Source: EPA GreenChill leak prevention maintenance checklist (receiver level log)
8. During routine maintenance in a supermarket machine room, you notice fresh oil seepage around a valve on a compressor rack's piping. What does EPA's GreenChill leak prevention checklist say to do?
- Wipe the oil away and look at the valve again at the next visit
- Tighten the valve packing and log it as repaired without testing
- Use soap bubbles or an electronic detector to pinpoint the leak
- Add oil to the compressor to make up for the amount that seeped
Show the answer
Answer: C. EPA's GreenChill checklist says to look over racks, piping and valves for oil seepage and, where it is seen, to use soap bubbles or an electronic leak detector to identify the refrigerant leak and pinpoint its exact location. Oil seepage usually marks escaping refrigerant, so wiping it off or adding oil leaves the leak in place, and a repair is not proven until it is tested.
Source: EPA GreenChill leak prevention maintenance checklist (oil seepage)
Safety · 16% of the exam
Personnel safety; job site safety.
9. While a technician disconnects a charging hose, liquid R-404A sprays onto the back of his bare hand, and the skin turns white and numb. According to the first-aid sections of the R-404A safety data sheets from National Refrigerants and Honeywell, what should be done?
- Soak the area in hot water so it thaws more quickly
- Pack the area in ice until medical help can arrive
- Bathe the area in lukewarm water without rubbing it
- Rub the area briskly to bring the circulation back
Show the answer
Answer: C. Both R-404A safety data sheets say that if there is evidence of frostbite, the area should be bathed in lukewarm, not hot, water and not rubbed; if water is not available, cover it with a clean, soft cloth and get medical attention if symptoms persist. Rubbing damages frozen tissue, hot water can burn skin that cannot feel heat, and ice makes the cold injury worse.
Source: R-404A safety data sheets, Section 4 First aid measures (skin, frostbite)
10. Your service van carries nitrogen and refrigerant cylinders standing loose in the cargo area between jobs. Under Cal/OSHA 8 CCR 4650(e), how must compressed gas cylinders be stored or transported?
- So that they cannot create a hazard by tipping, falling or rolling
- With the regulators left attached so the valves stay protected
- Lying loose on the floor with the valves pointed toward the doors
- Standing loose in the van, as long as each valve cap is screwed in place
Show the answer
Answer: A. Cal/OSHA 8 CCR 4650(e) requires compressed gas cylinders to be stored or transported in a manner that keeps them from creating a hazard by tipping, falling or rolling, so they must be secured. Valve caps belong on cylinders that are not in use (4650(f)), but they do not keep a loose cylinder from falling, and regulators are removed before cylinders are moved (4650(g)).
Source: 8 CCR 4650(e), (f), (g), Cal/OSHA Title 8 section 4650 Storage, Handling, and Use of Cylinders
Where to go from here
How the license works, from experience to fees: how to get a C-38 license. Everything about the course: the C-38 exam page.
Questions from our free C-38 test, written from CSLB License Examination Study Guide, Refrigeration (C-38), form 13E-38 (03-2026), for examinations scheduled on or after April 1, 2024. CSLB notes that the percentages are approximate. Reviewed 14 October 2026. Study guidance only; we are not affiliated with CSLB or PSI.