My craftsman 5hp 20gallon compressor trips my breaker at start-up? Craftsman 5hp 20gallon compressor tries to start up but trips my 15amp breaker.

It will run a second or two before doing it. unloader valve seems to be working, it moves in and out while trying to start, turning the regulator to low or max makes no difference, check valve works in and out, motor fan turns the piston without any snags, what could be the problem?

Craftsman 5 HP air compressor

Craftsman 5 HP air compressor

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Is this a new condition? What has changed in the power supply? My first check would be to see what else is pulling power from the same supply circuit.

When you say that it runs for a second or two, does it actually pump air, or is the motor trying to start for a second or two, and then the breaker pops? If this is the case, then I would consider your capacitor suspect. It may not be supplying enough boost power to get your motor going, the motor pulls too many amps for the circuit without the capacitor boost, and the breaker pops.

If neither of these are the cause send me a note as a comment on this thread telling me what you have done, and I’ll respond further.

If you haven’t looked at the page about BLOWS BREAKER OR FUSES from the troubleshooting page, I’d suggest that’s a good read.

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919.165500 (craftsman 33gal 6hp) exact same problem
by: Dave

Please post a follow up as this motor is nearly $300. I’d like to get this thing running myself without spending anywhere near that. I have narrowed it down to the motor and want to know if you or anyone else has solved and fixed this problem, also how much time and money was spent doing so.

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Just a thought
by: Anonymous

You may wish to check the circuit breaker.  They also get weak.