Air Conditioning Repair Cheat Sheet 2026

The 30 highest-yield Air Conditioning Repair facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. A time-delay relay in an AC control circuit is set for 5 minutes. What is its purpose? → To prevent short-cycle compressor restarts
2. A system using a fixed orifice metering device shows high suction pressure in winter. What adjustment is typically required? → Replace with a TXV
3. Which of the following actions is a direct violation of the EPA's Section 608 "prohibition on venting"? → Knowingly releasing R-22 from a hose when disconnecting from a residential system.
4. A hard start kit (potential relay and start capacitor) is added to a compressor. What is the primary purpose of this kit? → Increase starting torque to overcome high head pressure
5. In a rectangular sheet metal duct system, what is the primary purpose of installing turning vanes inside a sharp 90-degree elbow? → To reduce air turbulence and minimize static pressure loss.
6. Which EPA regulation governs the handling, recovery, and recycling of refrigerants used in AC systems in the United States? → Section 608 of the Clean Air Act
7. A car's AC blows cold for 10 minutes then gradually turns warm. What is the most likely cause? → Icing of the evaporator due to low refrigerant
8. When using an electronic leak detector on an HFC system, which type of sensor is most appropriate? → Infrared sensor
9. Before replacing a compressor, a technician should always: → Perform a system flush to remove contaminants
10. A technician reads 5 ohms between the compressor's common and run terminals and OL between common and start. What does this indicate? → The start winding is open
11. What is the purpose of a condensate trap installed on an AC air handler? → To prevent negative duct pressure from pulling sewer gases back through the drain line
12. When brazing refrigerant lines, why is it important to flow dry nitrogen through the tubing during the brazing process? → To prevent internal oxidation scale that could contaminate the refrigeration system
13. Which of the following is the most direct and primary indicator of non-condensables being present in a refrigeration system? → Excessively high discharge (head) pressure.
14. Which organization certifies technicians to fix refrigeration systems? → NATE
15. A residential split system is being installed in a garage. What special consideration applies to the condensing unit's electrical disconnect? → A fused disconnect must be within sight of and readily accessible from the unit
16. What happens to a start capacitor if it remains in the circuit longer than a few seconds? → It overheats and can fail or explode
17. How many BTU/hr are equivalent to one ton of refrigeration? → 12,000
18. When replacing a filter-drier on a refrigeration system, what is the correct procedure after installing the new drier? → Pull a deep vacuum before recharging
19. When recovering refrigerant from a system, the technician must use equipment certified to which standard? → SAE J2788
20. During a maintenance check, the technician notices the outdoor fan motor is drawing more amps than its nameplate rating. What is the most likely cause? → Failing motor bearings or a failing capacitor
21. In a standard refrigeration cycle, what is the primary function of the evaporator? → To absorb heat from the space to be cooled.
22. What happens in a condenser in a cooling and refrigeration system? → The refrigerant releases the latent heat.
23. Regarding the air temperature blend door in the circuit, each of the following statements is accurate. → It operates on CAN Class A network
24. Which measurement indicates proper lubrication is needed on older belt-drive blower motors? → Motor running hot above its rated temperature or unusual squealing noise
25. Which type of motor protection device senses both motor current and winding temperature to prevent compressor burnout? → Internal motor protector (IMP)
26. The process of adding heat to the refrigerant vapor after it has completely boiled into a gas is known as: → Superheating
27. A technician uses a megohmmeter to test a compressor's windings to ground. The meter displays a reading of 0.5 MΩ (megohms). What does this result indicate? → The motor insulation is breaking down and shorted to ground.
28. What does a nitrogen purge during brazing accomplish? → Prevents oxidation and carbon scale from forming inside the copper tubing
29. What problem occurs when refrigerant suction line velocities are too low in a vertical riser? → Compressor oil fails to return and accumulates in the evaporator
30. The following facts about an air conditioning performance test are all true, EXCEPT for → To avoid outside odor, operate AC System in RECIRC rather than FRESH mode