Quincy Air Compressor Help needed

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Chuter

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Location
Lexington, IN
A few months ago, I bought a used Quincy 3-1/2HP 220 air compressor for my new shop. About 5 years old, but only had about 20 hours on it. It ran fine at the seller's house. About a month ago the electricians finally wired my 220 outlet for the compressor. It ran fine then, too. I attached some piping for an outlet, tested it, it pumped up fine. A few days later, I noticed I'd left the switch in the auto position, the pressure gage said zero, and it wasn't running (although the hour meter was - it now said 83 hours). A little internet research pointed me to the pressure switch, plus it was relatively cheap, so I bought one and replaced it. Same result. At that point I checked the old switch, and it seems to have continuity when it should, both sides (black and yellowish white wire). In retrospect, the fact the hour meter was continuing to run should have told me it wasn't the switch.

That pointed me to the motor itself. Further disassembly, the motor turned by hand, as did the pump, although I didn't go very far with the pump - it quickly got hard to turn by hand, and I figured I was on a pressure stroke, so I stopped. Took the motor to a motor shop, a wire had come off internally. They fixed that, checked everything else, declared it healthy. Tonight I put it back together, turned the switch, and quickly heard a screech. Figured it was belt alignment or the guard rubbing. Shut it off, took off the belt guard, tried again. Still screeching, but noticed the pump isn't turning. Took off the belt, I can't turn the pump either direction by hand. it had built up a little pressure, but not enough to register on the gauge.

Am I just unlucky, or did I do something wrong? Anybody got any advice?
 
It could be, but I don't think so. I let air out at the end of my piping tonight. I don't understand how that relates to the pump locking up.
 
There's a pop off valve at the pressure switch that is supposed to bleed the head pressure off when the compressor cuts off when it hits max pressure on the cutoff switch. Try pulling the ring on it and see if it relieves any air from the pump.
 
Agree with post #5. There is a check valve that prevents the crankcase from pressurizing usually right where the air goes in the tank. If relief valve is bad it doesn't release the pressure the motor can't overcome the pressure. Like said most have an unloader valve at the pressure switch but not all. Some have them on the compressor head. Any pics of the Unit?
Check your check valve and bleed down said in post 5.
 
Thanks for the input, but so far it's just confirming what I've done. Oil is at the proper level. There's a site glass right at eye level to remind me. The unloader valve is how I discovered that I had built a little pressure with the new motor. Still not able to rotate it.
 
If you buy parts to repair it from Quincy, they're gonna bend you over with no Vaseline.....don't ask me how I know! :BangHead: Call Pacific Air Compressor and get what you need from them. I had to put reed valve plates on my Quincy and needed more gaskets because I screwed one up. Much cheaper from Pacific. They even hooked me up with one of their Technical advisors who helped me diagnose my problem. Quincy's are very good compressors, so I hope you get it fixed.

:thumbsup: Pacific Air Compressors and Air System Install | Portland, OR
 
Thanks for the heads up on Pacific Air Compressors. The Quincy site doesn't seem to offer any parts, just directs you to the local distributor, about an hour away.
 
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