My PC compressor flips the breaker at 120 psi

by Chase
(Bothell, Wa. USA)

First, thanks for taking the time and making the effort to help all of us newbies out here.

Now, I have a PC 135 psi 6hp 25 gal upright compressor. It will run up to 120 psi and then shut off. When it shuts off, it blows the 20 amp breaker. Doesn't matter what circuit its on, I've tried 3 or 4 different circuits and it blows them all.

Of course this doesn't happen 100% of the time. Just 99.999% of the time. In other words, it has operated properly 2 or 3 times over the lifetime of my ownership (I bought it used), and I have used it often in the last 5 years or so.

From what I have read it sounds like the pressure switch is shorting, and perhaps needs to be cleaned or replaced. Can you tell me if this is true, and if so, how I go about taking it apart, cleaning, and reassembling?

Thanks.

Chase

______________________
Bill says...

Chase, yup, it could be the pressure switch, but that might be too easy.

I think you do have a short to ground when the compressor stops, and it could be the switch, but it might also be a capacitor or the motor windings themselves.

Run it again though, this time with the cover of the switch off so you can see if it arcs a whole bunch when it reaches cut out pressure.

Or, see the check the capacitor page, and start there. If they check out OK, then the least expensive next step is to change the pressure switch. I doubt that it is possible to find replacement parts for them.

You can use some compressed air to blow the switch out if you want to try that.

Be careful with the power. 240 Volts to ground through you is a sure, quick, death!

Cheers,

Bill