Pressure switch failure ~ can't find a replacement

by Johnny
(Watertown, NY, USA)

I have an old, about 20 year old, Ingersoll-rand T21. Its like pulling teeth trying to find the pressure shut off switch for this old girl.


The compressor itself works flawlessly and by all means is the best investment our shop has ever made.

Its a 175psi 14cfm.. Where can i find a replacement since IR no longer makes one?? We're in a pickle and really rely on this thing to make business happen and don't want to risk hurting someone or the compressor itself. Thank god for safety release valves...

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Bill says...

A pressure switch is simply an electric switch that reacts to air pressure to either pass or stop the flow of electricity.

Therefore, using that concept as a base, you can jury rig one that will do the same thing (except perhaps toggle the unloader valve - careful about that).

Your local air valve and air cylinder supplier will also, I would expect, offer a range of compressed air pressure switches that could be configured to your air compressor.

They aren't complex devices. The difficulty is often in finding an exact replacement. Don't be exact, just duplicate the function.

Cheers,

Bill


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compressor does not automatically shot off

compressor does not automatically shot off. Brute 10 Gal

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Bill says....

If you are saying that your air compressor keeps running and the pressure in the tank keeps rising until the PRV blows, then stop using your compressor. This is dangerous.

With a compressor that won't shut off, I always look to the pressure switch as the problem first. The pressure switch reacts to the pressure to turn the compressor on, and also reacts to the pressure to turn the compressor off. It is an electro-mechanical device, and they do fail.

Cheers,

Bill

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compressor not cutting in when pressure is lower than that set at regulator

by Randy Marchinko
(Winnipeg, Manitoba, Canada)

My compressure is preset to 125 PSI.

I set my compressor regulator to 90 PSI.

After I work for a while with my nailer the pressure drops below 90 PSI but the compressor doesn't cut back in and build up the pressure. Even when I let it go for a while and it is well below 90 PSI it still doesn't kick in.

The compressor is a new CrispAir compressor distributed in Canada. The nailer works great.

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Bill says...

Randy, open the tank drain and bleed the tank pressure down with the compressor on. At what pressure point does the compressor start?

If it doesn't start at all, and the pressure in the tank reaches zero PSI, give the bottom of the pressure switch a sharp whack with the handle of a screwdriver.

If nothing still happens, I think your pressure switch may be the problem.

Cheers,

Bill

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ADJUSTING THE CUT OUT PRESSURE HOW DO

by Dave
(Coquitlam B.C. Canada)

HOW DO YOU RESET THE CUT OUT PRESSURE TO PUT THE COMPRESSOR INTO BYPASS MODE?

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Bill says...

Dave, you adjust the cut out pressure via the pressure switch. Have a read of the Pressure Switch pages to get more info.

As to putting it into bypass mode, I'm not sure what you mean by that. Could you please clarify this by adding a comment to this thread?

Thanks,

Bill

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My air compressor blows the circuit breaker as soon as i turn it on.

by Nick
(NY)

I got this used 6.5 hp 80 gal devil bliss air compressor from a friend for 250.00 so i wired it in direct, but as soon as i turn power on, it immediatley blows the circuit. Please Help

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Bill says...

You wire it for 220?

If you wired it to the correct voltage, drain the tank to zero, close the drain valve, and try again.

Did this make any difference?

Post a response as a comment on this thread, please.

Cheers,

Bill

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Feb 23, 2012
Ckt. breaker trips as soon as I turn compressor on.
by: Mario

I removed the belt and the motor ran OK. Then I removed the compressor outlet tube and the compressor ran OK and I could feel the air coming out of the compressor just fine. But when I try to turn the compressor on normally, the motor just groans for a couple of seconds then trips the ckt. breaker. Please help.
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Any change in the power supply. Lose the extension cord if you are using one.

When you remove the tube, and push your gloved finger against the outlet port to the tank, what happens?

If you bleed the tank down to zero PSI and then try to start the compressor, what happens?



Sep 24, 2011
Had same issue
by: Jeff

I had the same problem and I happen to have the same air compressor. 7 1/2 HP though. Electrician checked the wiring (even though I had been using the compressor for 3 years now). Checked out OK. Unhooked the belts, pump turns freely. Check valve, Ok. Even with no air in the tank, it would trip the breaker. Took the motor off (very heavy) and took it to shop to get checked out. Checked out Ok. Bought new capacitors, didn't help. Bought new pressure switch, didn't help. Week after having motor checked out, that expensive electric motor went up in smoke. Poof!!! Bought new motor, $600.00 later, compressor works fine. Lesson learned. Electricians know nothing. Air-compressor store people know nothing. Electric motor repair store people know nothing. Atleast they didn't help me. Good Luck!

Feb 03, 2011
Blowing circuits in NY
by: Nick

Yes, Bill, i wired it to 220, and the tank is already at 0, which is how i received it. Wow, thatnks for the super fast response.

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Just luck on the response. I happened to be on line when your question arrived.

Can you check (very safely) to be sure that the pressure switch is actually got power to it, and, since your tank is at zero pressure, power should be flowing through the switch to the capacitor.

Is that happening?

B.


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