Compressor motor humming ... trips breaker Question: My compressor motor hums and then trips my breaker, should I replace the motor? Answer: There could be several causes for the motor to hum but the most common would be because of a bad check valve. The check valve is located at the bottom of the exhaust tube where it goes into the tank. It is a one-way valve that keeps pressurized air from backing up onto the pump head. When the check valve fails, the compressor pump is trying to start under head pressure and the motor is not designed to handle this type of load. It will then draw high current until either the circuit breaker trips or the motor overload trips. The easiest way to diagnose a bad check valve is to listen to the compressor when it shuts off at max pressure. You should hear a short hissing sound coming from the unloader valve on the pressure switch that will stop after a few seconds. If the hissing sound does not stop, the tank pressure is leaking through the check valve onto the compressor head and also through the unloader valve. Upon restart of the compressor, the motor will start humming.

Item ID: 107 Last Reviewed: 12/14/2008 05:21 PM Product: Air Compressors Sub Product: ALL ITEMS   Was this helpful? Yes Somewhat No E-mail Print