AC motors are extremely widely used. However, as with any electromechanical device, AC motors can develop problems over time that can degrade performance or cause the motor to stop working altogether. If you don't have a spare AC motor at that point, it can leave you more or less unchanged. It's worth noting that with some basic electrical knowledge and proper diagnostics, many common AC motor problems can be identified and fixed.
First, check that the motor circuit breaker is not tripped and that the power cord is not securely connected or damaged. Measure the input voltage to confirm that it matches the nameplate voltage on the motor. If the power supply is OK, you will need to check the motor windings and capacitors. The windings, or coils, provide the rotating magnetic field for the rotating motor. Use a multimeter to test each winding to see if it shows continuity and the expected resistance. The capacitor helps start the motor; if it is defective or loose, the motor may hum or buzz, but not spin freely.
The motor fan and bearings are also parts you need to check. The bearings in the motor may need to be lubricated or replaced to restore free-spinning motion. You can use a screwdriver to gently turn the fan blades and bearings to see if they are stuck or worn.
Brushes are also a frequent failure factor. The brushes provide power to the rotating part of the motor, but they will gradually wear out and get damaged with use, and then they need to be replaced in time.
Performing these troubleshooting steps will help determine the cause of the AC motor problem. By replacing some parts and reassembling, your motor will soon be running properly again.