by Cary Honeywell
(Perth, Ontario, Canada)

I picked up a used Devilbiss PRFBC5525vp that likes to pop breakers. It starts up and runs for 2 seconds then crashes.

I replaced the capacitor in the motor hub (150 MF rather than the 135) and had the other capacitor checked at a shop. It was ok.

The motor turns by hand quite freely and even took the main outlet off to make sure there was air being pushed. What am I missing or is it that second capacitor?

_ Cary _
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Hi there Cary…

I tried to find the specs and a photo of your Devilbiss PRFBC5525vp air compressor on line with no luck, so I’m kind of shooting in the dark here.

Often, but not always, the compressor symptoms you describe are related to power supply.

Good that you checked the caps and replaced one. See the page under troubleshooting for how to check the other one if you wish.

As a comment here, tell me about how you are getting power to your air compressor, and the amperage of the breaker your air compressor is plugged into.

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Power
by: Cary

Thanks Bill. Yes. I couldn’t find a picture either. Everything else on the unit works with no leaks. Pressure on/off trips normally. (connected to another working air pump). The power is straight off the panel. I tried 15 amps first then 20. Same result. It doesn’t look like it could be wired for 220 either but that shouldn’t matter I think.

_ Cary _
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A 20 amp is good for a few HP. What’s the HP of your compressor?

Pull the line from the pump to the tank. Start the compressor. Still same problem?

And you can always upload a photo now if you wish. It will help all help you!

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Power
by: Cary

The motor is 5 HP. My other 5 HP compressor needed 20 amps but had run well at 15. This one blows the 20 amp breaker.

I tried removing the tube and it didn’t change the situation. There was air flow from the cylinder outlet so the head itself should be good.

_ Cary _
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I am not an electrician, but when I search for the recommended breaker for a 5 HP motor, I keep coming up with 40 amps.

B.

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Power
by: Cary

Uh.. yeah. Sorry. I took the motor off and checked the plate. AO Smith model K56A75B23, 120 V, 15.0 A, 60 Hz, Single phase, 3450 rpm, CW.

It may be possible to just replace the motor but it would be a shame if I couldn’t just fix it.

_Cary_

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Blows breaker
by: Anonymous

There is a check valve to hold the compressed air in the tank while the unloader valve drains the compressed air off the head of the pump. This happens each time the compressor shuts off. If the compressor is not draining off the compressed air from the pump it will try to start against a load and blow your breaker. Also if the check valve is leaking, you would be starting against the tank pressure and blow the breaker. Both are cheap parts to replace.

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Devilbiss blows breaker
by: Anonymous

Hi Bill, I have the same problem as Cary. Your last post you said to remove the line from motor to tank. I did that and it ran like a scared cat. Can you diagnose this for me please?

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Compressor runs like a scared cat!
by: Bill

You checked the capacitors?

By removing the line you removed the load from the pump, and it can run easily, and even with weak caps.

Or, check the tank check valve to see if it’s blocked, first.

 


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