By Quinten Plummer
Updated Mar 24, 2022

Single‑phase motors power a wide range of household appliances—from washing machines to mechanical clocks and generators. When a motor stalls or won’t start, a systematic approach can help you pinpoint the issue—whether it’s the motor itself or another component of the device.

Step 1 – Initial Inspection

1. Disconnect the motor from the power source.
2. Verify that the shaft rotates freely and that there are no burn marks or visible damage.
3. Inspect all switches and the starting mechanism; replace any parts that are worn or user‑serviceable.

Step 2 – Thermal Switch & Voltage Check

1. If the motor has a thermal switch, reset it after allowing the motor to cool.
2. Re‑apply power and attempt to start the motor. If it still won’t start, examine the wiring from the power source to the motor for continuity and damage.
3. Use a voltmeter to measure the voltage at the motor terminals. The reading should be close to the manufacturer’s specified voltage; a significant deviation indicates a supply issue and may necessitate a motor replacement.

Step 3 – Ohmmeter Diagnostics

1. Turn the motor off and set any starting devices to the “off” position.
2. Disconnect the power wires from the motor terminals.
3. With the motor powered down, use an ohmmeter on the terminals:

• Zero resistance (0 Ω) indicates a short circuit.
• Infinite resistance (∞ Ω) means there is no electrical path, implying a broken connection or damaged motor windings.

In either case, the fault is not user‑serviceable and a motor replacement is required.

Things Needed

• Voltmeter
• Ohmmeter

Warning

Always ensure the power is completely off before performing any tests on the motor.