Motor is free to turn but it will trip motor overload

by Jimbo
(Louisiana)

I have a Central Pneumatic Vertical air compressor (Model # 47065-125PSI, 21 Gallon, 4.5 Peak HP). The compressor worked fine when it was purchased 3 years ago. Now, motor is free to turn but it will trip motor overload, there are 2 Capacitors in the circuit are they Start and Run?

___________________________
Bill says...

Is the pulley that drives the pump also turning freely, even if with effort?

If the motor freewheels, and the pump cycles, then I would first look to the start capacitor. If it or they aren't working properly, the motor may be pulling too many amps on attempted startup for the circuit, and the breaker pops.

It may be best for you to remove the motor and take it, along with the attached capacitors, to an electrical motor rewind or rebuild shop. They can test to see what component is failing.

Cheers,

Bill