Troubleshooting air compressor

[vandersmash]

I was given a 10-year-old air Craftsman Air Compressor last year that wasn't working properly. So far, I've replaced both capacitors and the pressure switch and resealed all the leaky air fittings. It will run and build pressure, but not the proper pressure. It's supposed to cut off at 150psi, but it will only make it as high as 110-120psi. That's not all, though. It also won't restart at all. If I unplug it and come back to it later and plug it in, it will run again, but it will only make it up to about 80psi and still won't restart when it discharges. I've tried to look up more info on the compressor, but the model number is conveniently scratched off (see picture). Any ideas about what I should try next?

 

[larry4406]

Welcome!

My guess is that the unloader is not working and/or you may have an issue with the check valve between the compressor outlet and the tank.

 

[vandersmash]

I'll give that a shot. Thanks.

 

[The Cobbler]

It's supposed to cut off at 150psi, but it will only make it as high as 110-120psi. That's not all, though. It also won't restart at all. If I unplug it and come back to it later and plug it in, it will run again, but it will only make it up to about 80psi and still won't restart when it discharges.

first thing is compare your pressure to a known accurate gauge .. that set point is (usually) adjustable in the pressure switch . don't rely on an unknown pressure gauge
not restarting, does it try to start or just does nothing?

 

[finn]

The check valve was leaking on my little 30 year old PC pancake compressor. It healed before I got around to buying a new one or I burned out the windings because of the high current draw when starting.

This thread reminds me that I should order a new check valve.

 

[vandersmash]

first thing is compare your pressure to a known accurate gauge .. that set point is (usually) adjustable in the pressure switch . don't rely on an unknown pressure gauge
not restarting, does it try to start or just does nothing?

It just does nothing.

 

[The Cobbler]

sounds like either a bad pressure switch or a bad connection .

 

[finn]

It just does nothing.

Take the cover off the pressure switch. The switch on my well pump fell apart once. It was pretty obvious when I looked at it with the cover off.

 

[Shoreline_]

You replaced the pressure switch did you adjust the pressure to the desired cutoff setting? Turn that ***** in so it never turns off. Run it. When you get to 140 psi back off the adjustment until the compressor stops. Turn forward a smidge. Done.