blows main breaker in house

by Glen
(Redding, Calif )

my compressor motor will start up fine with no air in tank, however, when the tank is being used and the switch trips the motor to come on the motor wont turn and the breaker blows in the house.


I checked the one way check valve in the tank and it's free and looks good.

Once I evacuate the tank the motor starts up fine. If I remove the outlet pipe from the head I can hold my finger over the outlet and produce the same symptom of keeping the motor from turning with very little pressure over the outlet. Any ideas?

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Bill says...

Hi there Glen. Humor me. Go to the Valve page and click on the link to the Unloader Valve. Read this page.

This may be your problem. Check and make sure this is working before proceeding further.

Cheers,

Bill

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compressor restart issues

by Doug

I have a Mastercraft 4 gallon air compressor. If the tank is totally empty, the unit will operate to the safety cutoff pressure. As the pressure declines with use and reaches the cut-in pressure level, the unit attempts to restart but does not restart.

I think this is a pressure switch issue, but I am not sure. Thoughts??

Thanks for your advice.

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Bill says...

Hi Doug. When you say... "the unit will operate to the safety cutoff pressure. " I read that to mean that the compressor shuts off at the normal cut out pressure. If, in fact, it runs until the PRV valve blows, then yes, I'd suspect your pressure switch.

However, you also say "If the tank is totally empty, the unit will operate to the safety cutoff pressure." and that, to me, points to the Unloader Valve being the problem.

Check out the valves page and click the link to the Unloader Valve for more info.

Cheers,

Bill



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My air compressor locked up on me?

it was working but when i pluged it back in it locked up and now all it does is hum can you please tell me whats wrong with it? thanks shane

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Bill says...

Unplug it, open the tank drain valve, and drain the system down to zero. Close the tank drain valve?

What happens, Shane?

If it starts, I would suspect that your unloader valve isn't unloading.

If it still hums (I'm assuming it was the motor humming?)then your capacitor or motor may be failing.

Cheers,

Bill


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Do i need a unloader vavle on my swich

i have a presser switch with out unloader valve do i realy need a unloader valve

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Bill says...

Quite often, unloader valves are not part of a pressure switch, rather, a toggle from the pressure switch is what operates the unloader valve.

Do you need an unloader valve? Yes! I don't know of any DIY type air compressors that will operate without a functioning unloader valve. Why not go to the valves page, and click the Unloader Valve link to have a read about what they do?

You have a pressure switch without an unloader valve. Are you planning on using for a replacement on your compressor? What's wrong with the existing switch? Have you looked at the existing set up to see how the pressure switch and unloader valve combo works.

Do also have a read of the Pressure Switch page for more info on them too.

Cheers,

Bill

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compressor humms and blowes the breaker

by John
(Milford ct)

I have a devilbus 20 gal 5 hp oil less
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Hey John, nice to hear from Milford. Was near there a few weeks ago on the way to the Cape.

Please visit the Unloader Valve (use sitemap or follow link from Valves page) page, and have a read.

I think that your unloader valve isn't working, this adds too much load to the motor on re-start, and this blows the breaker.

Thanks for popping in.

Cheers,

Bill

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Air Compressor Tank Fills and Loses Pressure and won't run

by William
(Deltona, FL)

I have a campbell hausfled 20 gallon air compressor. When I start it, it runs great and fills up the tank with air. After using my air gun for a couple minutes, the tank empties. The drain valve is shut. You can hear the compressor trying to run but it doesn't.

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Bill says...

It may not start as it may not have enough energy to do so.

Pull the plug and drain the tank to zero. Close the drain. Plug the compressor back in and watch it as it runs up to cut out pressure.

Observe and listen for the unloader valve to function when the compressor reaches cut out pressure.

See the link from Valves to the Unloader Valve page if you aren't sure about what they are and do.

If the unloader valve doesn't function, that is your problem. Clean it, fix it or replace it.

Cheers,

Bill

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wont build up pressure under pressure

Goes up to 130 psi fine, when it is time to build pressure back up motor stalls then flips breaker on power supply. Tank has to be empty to build pressure.

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Bill says...

A motor that stalls on start up may be trying to start against too great a load.

One reason is that the motor itself has failed, and is shorting out.

The other reason that comes to mind is that your unloader valve may not be working. Click on sitemap, find unloader valve, and have a read. i think that this is your issue.

Cheers,

Bill

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Why does my compessor start pumping slow then speeds up

by Brian
(Louisiana)

It just started doing this. Sounds like it pumps slow and then speeds back up to normal speed. It does not always do it but the last few times I have noticed the sound of it and it sounds sick till it gets going.

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Bill says...

Brian, it could be many things.

The first thing I'd check, since it sounds as though it's starting under too much load, is the unloader valve.

Go to the valve page and click the link to the unloader valve. Make sure that this part of the compressor is working properly, and if so, then we'll need to look at what's increasing the load on start up. But first, check the unloader.

Bill

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