Sears 33 Gal. 6 HP compressor hums but doesn't start.

by Bill Silva
(Albuquerque, NM)

When I turn on the switch to my Sears 33 Gal. 6 HP compressor it hums but doesn't start. Before the problem, I would have to turn the switch on and off a few times before starting. It would even hum at that time but eventually it would start. Now it just hums but doesn't start. When looking at the switch, there seems to be gap in the switch relay that a spark jumps. That doesn't seem right. The gap is about 1/8" but doesn't pull the relay closed.

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Bill says...

It could be a number of things Bill.

The first thing I would check would be to ensure that the load isn't exceeding the motor capacity, and that means that the unloader valve is working.

Next, it could be the start capacitor not delivering enough of a kick to get the motor turning.

Could be the motor itself is failing.

Also could be, but not likely, that your pump is binding somehow, and that's overloading the motor.

I'd check the unloader valve first, and then take the motor into a rebuild shop and have them test the starter and the motor itself.

Cheers,

Bill