Craftsman compressor trips breaker on restart.

by Ross
(San Antonio)

Hello. My craftsman 5.5 hp oil free air compressor trips the breaker on the restart. The compressor starts fine from empty. But when the pressure switch triggers the pump to reengage it trips the breaker every time. I have replaced the unloader valve and the check valve. What is strange is I've taken the unloader valve away from the switch to attempt to manually engage to pin to release the pressure after cutoff and there doesn't seem to be any air in the line which leads me to believe that there is no pressure on the motor either. Any help is appreciated.

Comments for Craftsman compressor trips breaker on restart.

Click here to add your own comments

Feb 10, 2015
blows breaker (restart only)
by: Doug in

You need to find out where that 20V is going (or rather, where is being lost).

Try measuring the voltage at the outlet, then back toward the main breaker (might be a sub-panel before you get to the main panel)

There may be some voltage drop even back at the mains, but that "should" be very slight.

You are looking for where it drops the most. Then, we can figure out why. And/or as you go along, check the connections. If you are lucky, you'll find either a loose wire, burned contacts, or a bad circuit breaker. There are other possibilities, but try that first.

If you are not comfortable doing that, call an electrician for help.

Feb 08, 2015
Attached multimeter.
by: Ross

Hello again. Thanks for the reply. By attach a multimeter to the power I am assuming that I was supposed to place the multimeter on the switch where the motor draws it's power. Well I did get a chance to do this on the weekend and the multimeter registers 90 volts on attempted restart before blowing the breaker. Where should I go from here?

Thanks again for the reply

Feb 01, 2015
blows breaker (restart only)
by: Doug in

This is almost certainly an A/C power problem.

Put an A/C voltmeter on the power and see what happens to the voltage on restart. It should read at least 110V during restart. (If you don't have a meter, you could plug in an incandescent lamp on the circuit to see if it dims.)

Please post back with what you find, along with the model number of this machine.

Click here to add your own comments

Add your own question or comment. It's easy to do. How? Simply click here to return to Craftsman Compressor Issues.