Shop Air compressor DRIVING ME NUTZ!!!

[sawzall]

I seldom post here, (spend most of my time over on the H.A.M.B and Fordbarn)

BUT.. i have an issue I HOPE someone here might be able to help me solve..

shop air compressor, single stage, single cylinder 110 VOLT..

I SELDOM use this particular compressor, but I recently purchased an "air hog" that will require it..

the Issue I am having.. the air compressor runs for a few seconds (not long enough to build any appreciable pressure) then shuts off..
this process repeats and repeats..

eventually I am able to achieve 120psi.. BUT ONLY after the compressor has cycled several times..

I am absolutely beside myself.. BECAUSE..

I have checked fittings, replaced the Pressure Switch Control Valve (which includes the unloader valve)
I replaced the start / run cap..

I have checked and rechecked that wires etc are connected..

yet the problem persists..

(i have NOT found any indication of a "Thermal" reset or the like..)

any thoughts??

I am seriously ready to throw this thing to the curb.. AND I would have, IF it weren't in my loft, and IF removal would not pose such a PILE OF work..

 

[Brandonorr55]

Are the reeds bad?

 

[The Cobbler]

stuck or plugged check valve at the tank causing the pressure to build in the head and the pressure switch "thinks" the pressure has build up in the tank?

 

[firebirdparts]

Got a volt meter? You need to figure out what is stopping it.

 

[Flail]

Had one doing that. There was a one way valve between the compressor and tank. It got gummed up reducing the compressor output causing a short cycle.

 

[peter2772000]

Does the compressor motor initially short-cycle from the get-go, or only after it's been running for a 10-20 seconds or more? If it's only after 10-20 seconds, it could be the internal thermal overload cutting the motor out.

 

[Ole Slewfoot]

The thermal thing will also trip a lot if its actually a 220 motor and it hates teh 110.

 

[EOC_Jason]

If your motor isn't going into thermal overload (which would usually require you pressing a button on the motor to reset it), then you can probably rule that out.

Does the pressure switch connect directly to the tank, or does it connect in-line between the pump & tank? If it's in-line, then I would investigate your check-valve as it could be plugged preventing air flow into the tank and thus the pressure switch thinks the tank is at a higher pressure than it already is.

 

[dogdog]

I think all the possible solution are posted.

1) reed valves ( the one-way check valves in a flat spring discs usually inside the cylinders) Mine was bad on the 15 Gal Craftsman... won't go up to more than 20PSI-ish continuous to run.

2) check valve bad... this would normally be seen that the compressor would go up to pressure, then leaks down and cycles the compressor often and/ or won't hold pressure for long. my craftsman 33 gal was like that, I took it out and clean with an ultrasonic cleaner, it was some sort of cruds/corrosions hindering the valves from closing tight YMMV)

3) you have a bad pressure cutoff/cutin switch that it close/opens incorrectly, but you can just monitor your pressure and a voltmeter to monitor the contacts.

4) of cause that unloader valve might leak... but you can soap bubble test that fitting, and you would have heard air hissing out.

 

[peter2772000]

If your motor isn't going into thermal overload (which would usually require you pressing a button on the motor to reset it), then you can probably rule that out.

Usually, but not always. I've seen many larger single-phase motors with only an internal thermal cut-out and not many with the reset button. Then again, I'm in the HVAC field.
And, my own 5hp (pfffftttt) vertical does have afore-mentioned button

 

[sawzall]

Are the reeds bad?

this is my current thinking.. as I have checked the condition of the check valve (clean) and the pressure switch..

UNLESS the elcheapo motor has an internal thermal reset...

I need my compressor back NOW.. so anyone local to philly want a project?
I have a feeling I will be buying a new compressor this weekend..

 

[EOC_Jason]

You would know if the motor trips because it would be too hot to touch.

I've also seen strange things happen because the belt was too loose.

Reeds can get gunked up if you use regular motor oil vs non-detergent. It's pretty quick and easy to pull the head and check the plate with the reed valves. Though the gasket(s) will probably tear when doing so and you will need to order replacements or make your own.