plug compressor in and hit start and it hums very little and stops and i have to reset it

by Tony
(N.W.I.)

Plug compressor in and hit start and it hums very little and stops and i have to reset it

king craft 6 gallon 3.5 horse.

__________________
Bill says...

Did it ever work on the circuit you have it on now?

Sound like too many appliances drawing power from the circuit before it gets to the compressor, or the start capacitor is failing or has failed, or the motor itself might be flawed.

Before you check any of these further, unplug the unit, open the drain valve to drain the tank to zero, and plug it back in. What happens then?

Cheers,

Bill

Comments for plug compressor in and hit start and it hums very little and stops and i have to reset it

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Mar 12, 2013
start capacitor
by: Mike

Mine did the same thing. I discovered a wire to the start capacitor had a wire which appeared to be connected but would vibrate loose at times.

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Compresser hums when it should build up pressure.

by carlton norton
(ashford alabama)

when some air is used the air compresser hums instead of pumping more pressure

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Bill says....

Carlton; your compressor hums? Do you recognize the tune?

I think I do.

It's "my motor can't start as there isn't enough amperage in the circuit, or the motor start capacitor isn't working".

Those are the things I would check, as I suspect the humming is coming from your compressor motor that can't start when the pressure switch trips cut in at the low pressure level.

Cheers,

Bill


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Compressor won't start - makes hummimh sound

by Tony Brown
(France)

Hi, I wonder if you can help please. I have a Rondy RDY100CA50 compressor. I was using it okay and then it stopped as normal when the tank was full of air.

The trouble is it didn't re-start and just made a humming sound. I drained what air was left in the tank and opened the condensation valve- only a very samll amount of water came out. I checked the oil and that was okay. I then checked all the electrical connections and they were okay. I was using a power extension lead so I un-plugged it and plugged straight into the wall socket but still no joy.

Have you any ideas please and do you know how I can check to see if the capacitor is okay.
Thanks a lot

_________________
Bill says...

Hi Tony.

By dumping the air, and having the problem still persist likely rules out what my first guess was, the unloader valve. By draining the tank you effectively unloaded the air compressor, and if it still won't start, then your unloader valve is probably OK.

Plugging the compressor directly into the wall socket was a good move. Are you sure that there is nothing else new drawing power from the same circuit?

I tend to think it's your capacitor, too. I will be posting a page soon on how to check the capacitor. Not being an electrician myself, I'm relying on someone to provide me the info, and that hasn't come yet.

If anyone else knows how Tony can check his capacitor, please post.

Cheers,

Bill

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Dec 30, 2017
Testing caps
by: Bill

It very much does. Thank you!

Dec 29, 2017
Testing capacitors
by: Anonymous

It's rather difficult to test a capacitor without a multimeter that has a feature that allows you to test for capacitance directly.

Very few capacitors are shorted or blown open, generally speaking they are weak if they are a problem at all.

To see if your capacitor is within specification set the meter to the capacitance mode and apply the test leads to the terminals - it will take a few seconds as the meter is actually charging the capacitor and then reading it in farads. Be careful when testing capacitors because they do hold a charge which sometimes can be hazardous.

A continuity tester will tell you if it's blown open or shorted so if the only meter reads Infinity or almost zero owns the capacitor is toast. If it is simply week an old meter will be very very difficult to interpret correctly. Hope this helps.

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10hp star delta bogging down

by john
(Bedfordshire)

I have a sip 10hp star delta compressor which blew head gasket so I changed valve plate gasket and head gasket tightend pully belts changed oil cleaned return valve and checked all blow off valves now my problem is it starts and runs fine until 5bar then starts slowing down and struggling to run I also a few weeks prior to the head gasket blowing replaced the capacitor any help would be great

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