air compressor presure switch problems.

[RICH MUISE]

I just posted this on the Hamb...hoping somebody knows something about air compressors.

What am I missing here?
Last week my air compressor bleed valve on the pressure switch started to open but not close after the comprssor pumped up. I had replaced that switch 4 years ago and it's been working fine. I took the vlve apart, cleaned and reassembled with no difference. I replaced the switch this morning with a new one and still have the same issue. To clarify, the bleed valve I'm talking about is the one that the 1/4" hose from the tank is hooked to. I thought maybe possible since I replaced the switch with the same brand/model number I got a bad switch, or I screwed the new one up trying to adjust the shut off pressure limit, so I went and bought another switch of another design. Same issue....when it gets to full pressure and shuts off, the bleed valve opens and won't close back up. I'm assuming the reason for the bleed valve is just to relieve the pressure within the switch mechanism? It is not open while the compressor is pumping.
Any ideas?
The compressor is a 220 6.5 hp, 60 gal single stage.

[RICH MUISE]

Gotta love the Hamb...I had my answer 18 minutes after I posted the question. Apparently it's not the pressure switch, it is the check valve on the supply tube that runs from the pump to the tank. The bleed valve is mounted on, and triggered by, the pressure switch, and it's function is to bleed off pressure from the mentioned tube so when the compresser restarts it is not starting under a load. If that check valve is bad, it's not shutting off the air from the tank as it normally would. That is the reason the bleed valve in normal operation only bleeds for a few seconds.
If the bleed valve leaks when the pump is running, it's a bad pressure switch or bleed valve, but if it leaks when the pump is shut off it's a bad check valve.
OH well, I have 2 new switches I didn't need...ignorance gets expensive sometimes. The valve may be able to be repaired, but I'll wait until Monday to take the compressor apart when a have a small chance of finding a replacement locally if needed.

[Ford Blue blood]

I hate it when "learning" cost more in time and parts then asking.....I guess it is a "do it yourself" illness that I and many others suffer.

[RICH MUISE]

The saga continues, lol. Got a new check valve installed this morning after finally finding the right one at the 4th place I went to. Found it at Graingers. Got it installed and checked out...#$@!!!! same problem. WTH? I called the fifth place on my list which is actually an air compressor place and told him everything that was going on. He said I must have gotten a bad check valve from Graingers. They had some better ones in stock, so I went across town and picked up one of his. His are machined and the valve thingy is held in place with a circle clip, so they can be taken apart for cleaning. Anyway, got home and took the new Graiger one out only to find it was full of hard chunks of crap. Pulled the tube off the pump to find it was almost closed up with buildup. The buildup was hard as nails, so off to Lowe's for a length of M type copper tubing and some new compression fittings. My project for this afternoon....playing plumber.... No wait, the afternoon is almost already shot.
That crap is gotta be built up pretty heavy in the compressor head as well, but it's 12 years old, and not sure what I want to do with it at this point. It would be nice to replace the pump with a 2 stage. I was hoping to be spraying basecoat/clearcoat by Wednesday as I've only got a day left of blocking, looking more like Thursday or Friday.

[RICH MUISE]

FIXED!!! yahoo.
Everything is working like it should. I turned the compressor off after it pumped up to let it sit overnight. The reading on the gage in the morning will tell me if there are any leaks I haven't found. Also had to solder a pipe together with fittings as I don't have pipe benders for a short 90* bend, so I didn't want the compressor left on automatic until I'm confident my soldering is gonna hold. The pressure switch I used to replace the 120/80 is a 125/95, so I'm hoping that the faster on/off cycling will help a little keeping up with the paint gun.