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How do I know if an AC motor is going bad?

2022-11-01 10:47:37

They used AC motors in a wide variety of applications, so if they fail during use, they can cause many problems. Here are some ways to tell if an AC motor is faulty.


Judging by the sound. When the ac motor is running, if there is a "humming" sound, the sound does not change from high to low, which is a normal phenomenon. If the sound is thick, and there is a sharp "humming" and "hissing" sound, it is a harbinger of failure, the following reasons should be considered:

  • The iron core is loose. The change of temperature from high to low will deform the fixing bolts of the iron core, causing the silicon steel sheet to loosen and generate large electromagnetic noise.
  • Rotor noise. If there is a "dong dong" sound like when drumming, it is because the rotor iron core and the shaft are loose when the motor starts or stops suddenly. If the situation is serious, it needs to be disassembled for inspection and repair.
  • Bearing noise. If you hear a "crunching" sound, it is caused by the irregular movement of the roller gun in the bearing. The sound of "hissing" is the sound of metal friction, which is generally caused by the lack of oil friction in the bearing. The bearing should be disassembled and greased, etc.
  • Olfactory judgment. The motor has no peculiar smell in normal operation. If it smells a peculiar smell, it is a fault signal.
  • Temperature judgment. Touch the motor housing with your hand. If it is very hot, it may be overloaded or the voltage is too high.

What happens if an AC motor goes bad?

A customer encountered such a situation before, and the feedback he gave was: The cooling fans won't turn on. The fan turns on when the AC is running, but the blades rotate slowly. You can hear a rattling noise coming from the condenser unit. It smells like something's burning.


It is very important to judge the fault of the motor according to the abnormality of the motor in time. If some faults are not dealt with in time, it may damage the motor and damage its performance. The key to ensuring your equipment runs at peak performance for as long as possible is to conduct regular inspections of your facility.

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