So my air compressor quit working. I replaced both capacitors and it won't kick on. The motor will turn a very slowly then trip a breaker. I opened the motor up and found a thermal switch inside. I don't think that is the problem. The motor windings are not burnt and the bearings are free. Anyone know what might be wrong with it?

typically inside the back plate (end bell) of the motor is a centrifical switch that applies power to the start windings until it is up to speed -- sometimes easy to reaplace -- sometimes throw the motor.

H2ORat. Here is s picture of that bell your talking about. I circled a cluster of contacts on the back of the electric board. Is this what your talking about? They are a little corroded. I intend to clean them up. Tomorrow I'll reassemble the motor a turn it on without connecting the the air lines. Hopefully the motor will run. If it does then I'll know the problem lies in the circuit board.

Mine will do that once in a while. Drain all the pressure off the tanks. That usually gets mine to fire up. Also, if it's cold or has an extension cord ahead of it, mine doesn't want to start.

Yep that is the switch -- definately start it with no load first then put the berlt back on.

If the thermal switch was bad, it wouldn’t do anything. Saw motors need a good blow job once in a while. Sometimes that’s all it takes. Take off the end bell and blow out the windings/switches etc…just fyi sometimes capacitors can check good and be bad.

Thanks everyone for the information.