Compressor Blows
       Motor Breaker

What's going on with the air compressor when the compressor blows motor breaker? Here are some questions and responses about compressors that blow the motor breaker. I hope they help.

Question:I have been thru all the test cases with the unloader valve and the check valve and all is fine with these components.

I have narrowed my problem down to this.

Compressor Blows Motor Breaker Switch

My twin cylinder air compressor restarts at cut in where the motor struggles and the compressor motor lopes between start and run and then the motor breaker cuts the motor off.

I have a pressure saftey check valve in the air tube running between the two cylinders. If I pull this pressure valve out when the motor starts at cut-in then the motor starts up and running fine and when I release the safety check valve it will continue to run to the cut-off pressure. There seems to be some type of pressure imbalance that build in the air tube between the two cylinders.

The reason I say this is because if I block one of the intake ports on one of the cylinders then the motor starts right up and the compressor starts running fine and then I can unblock the cylinder port and it will continue to run to the cut-off pressure.

However everytime I let the compressor restart with out either releasing the safety valve between the two cylinders or blocking one of the intake ports the motor struggles to get the compressor running lopeing between start and run and the motor breaker cuts off after about 2 seconds or so.

What could my problem be???

My Response

It might help other contributors to know what make and HP of compressor.

What my thoughts are is that the intake valve on the second cylinder may be impaired somehow, creating back pressure in the line between the two, and essentially, overloading the compressor motor on startup.

Visitor comment

The Compressor is an Ingersoll Rand Garage Mate 20 Gallon


Every time I try to start my air compressor it hums then the breaker pops. I have taken the cover off of the back and turned the fan-wheel and can hear the cylinder popping but won't start while plugged in.

My Response

Turn it off, drain all the air from the tank, and then try to turn it on again. Any change?

Visitor comment

I have used all the air up. There is no air in the tank. The compressor won't start to build up any pressure.

My Response

I asked you to do the drain the tank thing as that simulates the operation of the unloader valve. Air trapped over the piston can overload the motor on start up, and cause your compressor symptom. So, next, any change in the power supply Dan, stop using an extension cord if you are, and make sure nothing else is pulling power from the same circuit your compressor is on at the same time it's trying to start. If that's all good, make sure your intake filter is clean, and then, it's time to check your capacitor. See the how to check the capacitor page on this site.