Compressor motor shuts off after 20 seconds.

by Mike

I have a Craftsman oil-less compressor, 6hp 33 gallon with an AO Safety motor. It runs for 20 seconds and then trips my surge protector. I am running motor only, the piston and such are not hooked up. I tried to replace the's not them. The motor runs the same even with the capacitors NOT plugged in. Everything is clean, no broken or burned wires. I did notice a round (sensor or pick-up of some sort?), quarter size component that is attached to the back of the motor body that gets pretty hot to the touch but I don't know if its replaceable or what it's true function is.

Any ideas?

Bill says....

Mike, if it's tripping the surge protector then it's pulling more amps than the circuit can handle. It's not clear from your comment (at least to me) if it's tripping out after 20 seconds when it's not coupled to the pump.

Regardless, to me it sounds like an electrical fault, and the motor is the likely culprit. Get it checked, would be my advice.



Comments for Compressor motor shuts off after 20 seconds.

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May 10, 2011
20-30 second shutoff
by: Anonymous

I have a similar problem. I was going to pull motor apart next . I might find the problem. I hope?

Apr 27, 2011
Figured it ou
by: Mike

I figured the problem out!!!!! Took apart the motor for the 3rd time to look around again for the issue. Found a burned raw copper wire in the windings, it happened to be the one connected to the start capacitor, soldered a "connection wire" to it and all is well. I don't know if this is safe or not but it works for now. I will be double checking to make sure I can leave it this way.

Apr 24, 2011
Compressor motor shuts off after 20 seconds.
by: Mvalent000

I bought the motor/compressor knowing it had a problem with the motor( I am trying to fix it myself...with help from anyone who has electrical knowledge)and use it for a back-up to the compressor I have.
I currently run the same size compressor off of the same outlet/surge protector without any issues at all.
I only use the surge because I can plug multiple things into it.
That being said, and as mentioned before, the problem is the motor and not anything else.....pressure switches, outlets, etc.
What I did find when I was testing it was (and I don't know if I mentioned it in the last thread) the thermal overload pick-up or switch thingy (a little bigger than the size of a quarter with 3 wires connected to it) gets pretty hot within that 20 seconds of the motor running. This is the only thing I have noticed thats out of the ordinary.

Apr 24, 2011
Surge protector tripping...
by: Anonymous

Check the amperage that your "surge protector" is capable of handling.
6 HP consume lot of juice (Amperage) for a regular surge protector.
Check the "protector' amperage capability, you are exceeding it's internal breaker capacity.
Besides, you DO NOT NEED a surge protector in a compressor, they are only used to protect electronic equipment from things like compressors he he.
Your compressor is OK, loose the "protector" and plug it directly to the wall.
WARNING : Make sure that you are not exceeding the Amperage capacity of your wall outlet, or you may be at risk of creating an electric FIRE hazard; (probably inside the walls) if your line breaker is miscalculated for the wire size.

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i have a craftsman air compressor - then wont restart

new presure switch and it turns on and builds presure then shuts off at 175 . then wont restart without blowing the breaker
Is the unloader valve working?


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