Motor fails to start?

Last updated: May 29, 2026

If your motor will not turn or run, the following causes and steps can help you check the problem. It may be caused by low voltage or severely unbalanced voltage, and incorrect motor wiring is also a common cause of starting failure. First check the power supply fuses, then verify the wiring follows the motor wiring diagram correctly. Measure the voltage at the motor terminals; if it is within the operating range, check whether the driven load exceeds the motor capacity. This may be due to incorrect motor selection causing excessive load, for example choosing a small motor when the application needs a larger one, or the load end being jammed by a foreign object. To rule this out, remove the excessive load if possible, or disconnect the motor from the load to confirm the uncoupled motor turns freely. Below we explain common causes of motor starting problems and how to resolve them.
 

Is the motor not turning a wiring problem? How do I check motor wiring?

Unreliable or incomplete wiring can cause several motor problems. Terminals may be loose, the specification may be wrong, or the wiring may be damaged or worn, all of which can prevent the motor from starting properly. Carefully inspect all wiring in the motor starting circuit. Refer to the motor wiring diagram on the nameplate or in the user manual, and check along the wiring path.
 

What are the symptoms of a damaged motor starting winding?

Another common cause of motor problems is a damaged starting winding. The winding itself does not naturally wear out over time; instead, poor contact combined with vibration loosening can raise contact resistance and cause local overheating, leading to abnormal current that burns out the winding. In addition, an incorrect number of turns during rewinding repairs can also prevent the motor from starting. When inspecting, first check the winding for signs of scorching, discoloration, or open circuits, ensure the contacts are securely fastened, and use a winding of the correct specification.
 

Why does my motor fuse keep blowing?

This is one of the most common causes of a motor failing to start completely. If a fuse blows somewhere in the system, replace it with another fuse of the same amperage, or reset the breaker before restarting the motor. Fuses blow for various reasons, most commonly excessive current, so if it keeps happening the motor may need additional evaluation to prevent excessive current from causing problems or even burning out the motor.
 

Is hard starting on a single-phase motor caused by a bad capacitor?

Single-phase motors use a capacitor, so the motor should be run regularly and the capacitor kept in good condition with sufficient capacitance. When the starting capacitor has insufficient capacitance, the motor may start with difficulty or require several attempts to start, in which case the starting capacitor may need to be replaced.
 

Can corroded control switch contacts affect motor operation?

Switch contacts can corrode due to repeated use, current surges, and similar issues; inspect the control switch carefully when the motor will not run. If contacts are burnt, dirty, or corroded, the current flowing to the motor may become abnormal. During routine maintenance, clean any dirt on the control switch contacts to avoid poor contact affecting the current and motor operation.