When troubleshooting single-phase compressor motors, it is important that the technician:

• A. Check the start relay, start capacitor, and run capacitor.
• B. Check only the run capacitor.
• C. Replace the compressor without testing.
• D. Inspect the refrigerant level.

Answer: (A)

Troubleshooting single-phase compressor motors centers on the devices that start and sustain rotation. The start capacitor provides a brief surge of current to create starting torque, the start relay switches that capacitor in at startup, and the run capacitor helps improve running efficiency and torque. If any of these parts are faulty, the motor may hum and fail to start or run weakly. Checking all three captures the most common electrical faults that prevent starting. Other options miss key failures—for example, testing only the run capacitor can overlook a bad start capacitor or relay; replacing the compressor without testing ignores simple, reversible issues; refrigerant level affects cooling, not the motor’s starting sequence. So the best approach is to inspect the start relay, start capacitor, and run capacitor.