How to Troubleshoot Single Phase Motors

Single-phase motor

Single-phase motors are found in a long and diverse list of devices like washing machines, mechanical clocks and generators. if you experience a problem with your single-phase motor, a few simple troubleshooting steps can help define whether the problem lies in the motor or with some other part of your device.

    Disconnect the power source from the motor. Check that there the shaft is not stuck and that there are no signs of burning. Check any switches or starting mechanism. Replace any user-serviceable parts.

    Reset the thermal switch on the motor if there are no visible signs of damage. After the motor has cooled, start it again. If the motor fails to start, check the integrity of the wiring from the power source to the motor. If the wiring is intact, use your voltmeter to test the voltage of the motor; the voltage may not be exactly matched to the manufacturer's specified voltage, but it should be close. If the voltage is off by a substantial amount, you will need to replace the motor.

    Turn the motor off if the voltage is correct. Switch any starting devices on the motor to the "off" position and turn the power off. Disconnect the power wires to the motor and use your ohmmeter on the terminals where the wires were connected. Readings of zero indicate a short, and readings of infinity indicate that there is no resistance in the motor and the circuit is unimpeded. In either case, there are no user-serviceable parts to remedy the problem and you will need to replace the motor.

    Things You'll Need

    • Voltmeter
    • Ohmmeter


    • Always be sure that the power is off before testing the motor.