Not building pressure, won't start

by Donovan
(Lethbridge, Alberta, Canada)

I have a 3hp electrical oil compressor with a 5 gallon tank


So Yesterday, while I was working, I noticed that the the compressor kept running for a long time, rather than turning on and off when the pressure gets low. I turned it off to listen for leaks... nothing. I then drained the tank and started it again, and it sounded normal, but took forever to build pressure (which it eventually did... and still wouldn't stop running.

Today I plugged it in and started it, and it made some quieter noises, sounding like it's trying to start, then cut out and the reset button would pop out. I reset it and tried again several times.

Can you tell me what the problem is and how to fix it?

Part 2: I tried it again and it ran fine, except that, once again, it took a long time to build pressure and would never shut off (but never build past 100psi or so either.
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Donovan...

It sounds as though your motor has undergone some issues (not good ones) as a result, I suspect, of running too long without adequate time for cooling.

There are a number of reasons why an air compressor will not build pressure. Please see the Troubleshooting section on the site map page and follow the links to pages relating to why compressors run but will not develop pressure. Please have a look at those pages to check some of the things they refer to and post here telling us what you found.

Cheers,

Bill

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motor runs but trips thermal overload in about 10 seconds

by greg
(Tennessee)

the motor runs but will trip the thermal overload in about 10 seconds. I disconnected the tube from the compressor to the tank and the motor runs and will produce air from this tube.
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But, Greg, will the motor trip after about 10 seconds with that tube disconnected?

If not, then you might consider pulling and cleaning the tank check valve, usually found where the tube from the pump head reaches the tank.

Did that make any difference?

How is the power supply to the compressor? If you are using an extension cord, will the compressor run properly if you plug it right into a receptacle?

Cheers,

Bill

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Air compressor takes 45 minutes to fill.

by Howard Gfelner
(West Hills, CA, USA )

I converted my 40 gal, 1 hp compressor to a 3 hp ( motor & pump both 3 hp) with harbor freight parts. Now my compressor takes 45 minutes to fill where before the conversion it would only takes 15 min or so. Once it is full it's fine. Pump pulley is 12.5" & motor pulley is 2.37", motor rpm= 3450 on 230v.
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Howard, see the Troubleshooting section linked from the site map page, regarding compressors that will not build pressure.

Cheers,

Bill

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