Porter Cable C7550 air compressor motor will not start

by Greg

Hello, I have a Porter Cable C7550 air compressor.


It has a 230V 1phase motor.

I have the belt disconnected and the motor still does not turn under power.

I can turn the motor by hand and it spins freely.

It shows no signs that I have applied power when I turn it on. It doesn't hum, twitch, or do anything else. It still spins freely in either direction with power applied. It does not trip the circuit breaker.

I attached another 230v item to the same outlet and it works.

I started by testing the pressure switch and have power on the line and motor side. I checked for power on both sides of the thermal overload switch and power is present.

I tested for power at the start and run capacitors and they both have power on them.

I disconnected the capacitors and read the capacitance on each. The run capacitor is rated 50mf and reads 40.9 on my meter. The start capacitor is rated 327mf and climbs from about 300 to around 700 on the meter.
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Greg, an excellent job working through the reasons why your air compressor motor doesn't start. Wish I had your skills!

OK, simply, if you have power flowing to the start cap, and nothing happens on the motor, then it's my opinion that the power is not getting through the start cap to get the motor going, or, you have an open line somewhere in the circuit that is preventing power flow.

Cheers,

Bill

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Apr 15, 2013
Got it Bill!
by: Anonymous

Hi Bill,

I took the back off the motor to see if I could find this open line. Sure enough, the other Hot that goes directly to the stator had become disconnected. It had an inline spade connector that was just dangling there. I pushed it back together, gave it a little squeeze with the pliers to tighten it back up and reassembled the motor. It took a little adjusting to keep the armature from rubbing the stator, but it is running good now. Thanks.
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Glad to have been what little help I was. Good on you for digging into the guts to find the compressor wiring problem yourself!

Cheers,

B.

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Porter Cable air compressor is blowing breakers

by frank
(talladega al.)

I have a portable air compressor,4 gal. 120v./15a/60hz. model cpf23400s-2.

it is a 3h.p.peak or 1.6 h.p.running,oil free.

when I plug it in the wall it runs like a 220 v on 110 ,for a few seconds then it blows my shop breaker,which is a 30 amp screw in breaker.

this motor has two starting compassitors on the end of it.

so I am wandering if my motor is burnt up or how can I test it?

i am aware of how dangerous electricity is.it has porter cable written on it. so I assume that is the name of it.
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Frank, good to have respect for electricity, and I don't mess with it unless I'm sure what I'm doing.

Is there air in the tank when you are trying to start it? If so, try emptying the tank first and then trying again.

If it starts with an empty tank, but not when there is pressure in the tank, the first thing I check is to make sure the unloader valve is working.

Yes, it could be the start capacitor to, but the "try when the tank is empty" test is a good first step.

Add a comment here with your findings if you wish.

Bill

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will not gain presser

by howard neil
(lewisburg kentucky usa)

I have a 6 gal porter portable, last year it ran good. today it runs but will not bring pressure up
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Could be a bunch of things, Howard.

If the pressure in the tank rises to, say, 20 PSI and stops there, that is often an indication of a blown gasket or problem valve in the pump head.

See the sitemap page, under troubleshooting, for more information about why air compressors run but do not build air pressure.

Cheers,

Bill

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Porter Cable C2006 cycles once and won't kick on again

Porter Cable pancake air compressor

Porter Cable pancake air compressor

Porter Cable C2006 runs normally for typically one cycle building up pressure correctly.

When it needs to kick on again (due to using a nail gun and lowering the available pressure), it then attempts to run again but makes a "grinding" noise while trying to kick on again.

After a few tries it eventually does kick on again and work. It did not originally do this and would like to fix it.

It also occasionally "hisses", leaking air for what seems to be no reason. Maybe a pressure relief valve is going bad? Not sure.
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Could be just wear and tear on the compressor. You don't indicate how long you've had it or how often it's used.

Can't figure out why it would make a grinding noise.

Hissing air could be downstream air bleeding back through the regulator, maybe a tank check valve.

This is a "mini" type air compressor with limited life expectancy if being used daily.

Any other thoughts?

Bill

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