IR Compressor Runon Problem?

[Red Baron]

Came into ER this afternoon and it was very smoky and had that distinct smell of overheating compressor. The tank and pump were very hot so I tried to shut it off via the on/off lever on the controller but it wouldn't go off. Had to trip the breaker. The pump was low on oil, added about 1/3 quart, let it cool awhile then fired it up again - it kept running and the popoff eventually opened.

I have my little compressor plugged into it to get me by until the am; can any give me hint on what might be going on?

 

[I.B. Washincars]

It would pretty much have to be a stuck pressure switch or motor contactor. Either one being stuck could cause run-on. You may not even have a motor contactor. Either way it should be pretty easy to diagnose. Just take either of the switches apart and see if it has contacts that are melted together. If you can't see the contacts a volt/ohm meter should nail it down pretty quick.

 

[MEP001]

I've had the same issue with an I/R compressor - the contactors seem to be almost undersized and stick closed. While it's running, whack it with the handle of a screwdriver and it will unstick for a while, but it will eventually stick again. If it wouldn't turn off by the lever on the pressure switch, it's definitely not a pressure switch problem.

You don't need to get a replacement from I/R. You can get a universal one and replace the whole box for about half the cost. All you need is a minimum 30A contactor with 230V coil.

 

[soapy]

Sometimes you can file the contactors and clean them up without replacing them.

 

[I.B. Washincars]

If it wouldn't turn off by the lever on the pressure switch, it's definitely not a pressure switch problem.

With the few details that RB gave you can't be sure that his compressor even has a contactor/starter. If it is controlled through a pressure switch only, couldn't a stuck switch indeed be the problem?

 

[MEP001]

With the few details that RB gave you can't be sure that his compressor even has a contactor/starter. If it is controlled through a pressure switch only, couldn't a stuck switch indeed be the problem?

I should have added "If the compressor has a remote contactor." I/R only has two compressors that use the switch to directly control the motor, and either of those would be too small to supply air for a D&S 5000 and some SS bays.

Sometimes you can file the contactors and clean them up without replacing them.

That's only a temporary fix. The contacts are coated to prevent arcing and sticking, and once that's gone it will only get worse. The ones I/R use don't come apart easily either, and the contacts are inaccessible.

 

[soapy]

I have always used Square D contactors that I supply. I have watched my electrician clean the contactors up on many things with great results and long term results.

 

[Red Baron]

'Twas the pressure switch and has now been replaced. In the meantime I had the entire wash running on my tiny 10 gallon compressor and it was running hot so I decided to get a bigger one as a backup, but not so big that I can't use it elswhere. Picked up a 20 gal Husky at Home Depot for just $199 - when I came into the ER this morning it had been running all night, developing only 40 psi even when I took offf the hose. Took it back to home Depot (bad pressure switch!) and got another one just like it under warranty. This time though HD gave me one that came with an impact rathchet, 1/2 impact wrenche, and assorted accessories...always fun to get a bonus! I offered to give the tool back since the compressor I bought yesterday didn't have one, but they said no, same price anyway.

I have compressors running out my ears now!