Compressor slows down then clicks

by Jeff
(CA)

So, just bought a compressor that sat outside for a year or so(yes was rained on). I dumped the water out of the head, changed the oil, and it appears the compressor spins fairly nice considering the damage done.

I took the ,belt off the compressor and motor spins fantastic. I put belt on and opened air valve completely fired it up and it runs fantastic.

The problem lies when its running under load(it starts up at 0psi no problem) but at approx. 50 psi or so the rpms slow way way down almost to a stop, then the motor cycles on and off, clicking(what appears to be resetting). I can see sparks in the motor housing according to the clicks.

Other notes are: the pressure switch will leak when the lever is in the 'off' position and there is pressure in tank. However, with pressure in the tank and lever in 'on' position(the only way to stop it from running is to unplug it otherwise it cycles as stated above), the pressure switch does NOT leak.

Also, I let the compressor/motor cycle upwards of 30times and no breakers went, nothing was burning, and the reset button on motor did not pop.

So, what the heck is going on here!? I pulled the in tank check valve, pushed air through it in the opposite way and did manage to get air through it, but was so miniscule I cant see that being an issue.

_____________________
Bill says....

I think you have motor damage which manifests itself under load.

From the sound of it, your check valve is leaking, and you may have an issue with the unloader valve, though I can't be sure.

It were me, I'd first have the motor checked under load and if it checks out, I'd replace the pressure switch, and then tackle the check valve.

Cheers,

Bill