5 hp 80 gallon upright compressor continues running after 145
by Mark Schuster
(Princeton, WI )
I have a 80 gallon 5 hp Sanborn upright compressor. I am a luthier and until a couple weeks ago this has worked flawlessly. This is my third Sanborn compressor, I still have my first one that I purchased in the early 90s. Runs great.
But 2 weeks ago I heard the compressor kick on. I keep it in the basement of my shop. Then instead of shutting off I heard the relief valve blow. I ran down stairs and shut the compressor off from the pressure switch and pushed in the relief pin. The air stopped leaking out and the compressor seemed to work fine for a couple weeks.
A half hour ago I was spraying lacquer on a guitar. The compressor kicked on and again in about 5 min I heard the relief valve open. I ran over to shut it off from the pressure switch and this time it would NOT shut off. I ran over to the breaker box and turned it off. I removed the cover from the pressure switch. The gauge says just over 145 pounds and I can tell the switch is still calling for air. With the power off when I turn it to off I can see the contacts open. When I turn it back to auto the contacts close. I am guessing that the switch is starting to go. Hope not. Any help is appreciated. Thanks
Mark L Schuster