Air Compressor Motor Trips Breaker

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Old 03-04-12, 08:11 AM
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Air Compressor Motor Trips Breaker

I have a Campbell Hausfeld vt633300aj air compressor that when I turn it on, the motor hums for a few seconds and then trips the breaker.

I pulled the belt off of the motor and the motor then turns on fine. I can turn the fly wheel on the compressor by hand and it isn't locked up.

Anyone have any suggestions on where to go from here as far as troubleshooting?

Thanks!
 
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Old 03-04-12, 08:42 AM
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Although I don't see it in the parts breakdown here....Campbell Hausfeld vt633300aj parts breakdown on ToolPartsDirect.com my first thought is that you need a new starting cap for the motor.

Should be under one of those humped covers on the motor I believe.
 
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Old 03-04-12, 10:19 AM
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Okay so I pulled both of the caps off the motor. Any idea which one is the starting cap?

One is black and is a 145-174MFD 220VAC

One is grey 40uF (I think uF) 370V 50/60HZ
 
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Old 03-04-12, 10:45 AM
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Sorry...that's something i wouldn't know. I'm sure one of the Pro's will pop in.

Does either one look bulged or leaky? Might be pretty cheap to just replace both? You'll probably have to find an electric motor shop. Ha....or maybe Grainger...looks like they have some exact matches to what you stated...depending on sizes. Looks like the 145-174 is probably the start cap....the smaller ones are all labeled as run caps.

Start Capacitor, 145-174mfd, 220-250 V, Rnd - Capacitors - Motor Supplies - 2MET4 : Grainger Industrial Supply
 
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Old 03-04-12, 11:15 AM
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A few more questions - is it 120 volt or 240? What size breaker is it plugged into? was it previously running on that circuit?

btw - welcome to the forums!
 
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Old 03-04-12, 11:35 AM
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It is 120V. It was working fine and I used it on the same circuit as I always have. I also tried another circuit and no change.

I found the "black" capacitor on ebay for less then $10 including shipping so I went ahead and just ordered it to see if that fixes it. Also the cap was maybe a little bulged as it didn't fall right out of the cover and I had to pry on it a little to get it to fall out. Also I tapped a screw driver over the leads on the cap and got nothing as I assume if it was working properly it would have had at least a spark from a charge still in it?
 
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Old 03-04-12, 11:42 AM
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If it was bulged...thats most likely the issue. Was it the higher rated (145-174) one?

You probably wouldn't have gotten a spark. After you stop the motor or turn off the power it will normally bleed off pretty quickly, depending of the wiring. Always a good practice to short them though.

We used to charge up caps..then disconnect them from the source and toss them to an unsuspecting person.
 
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Old 03-07-12, 04:03 PM
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Well I got the replacement capacitor today. No go. Still does the same thing. With no load on the motor it turns on and runs just fine. Put the compressor belt back on and it trips the breaker. I tried to turn the compressor wheel when I turned it on and it acted like it wanted to maybe try and run the compressor but it really didn't do much and soon the breaker tripped.

I am considering tearing the compressor apart at this point unless someone thinks it is still a motor issue? Although if I do that I am not sure what I would be looking for. Anyone have any ideas where to go from here?

Thanks
 
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Old 03-08-12, 07:51 AM
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wait

Let's try a few simple troubleshooting steps before you tear up the pump. Some may be redundant, improvise as you see fit.

1. Is the pump head unloaded when you try to start
2. Are the motor pulley and pump flywheel perfectly aligned
3. Is the belt tension properly set, not too tight
4. Can you spin the pump by hand when disconnected from the motor

Report back with your findings. If the motor did not run fine on its own, I would guess that the centrifugal switch was faulty. But since it does, can you get it spinning and put a current meter on it? If it's drawing more amps then specified on the nameplate, the widings could be partially damaged
 
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Old 09-15-14, 09:50 AM
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I know this is an old thread, but I was having the exact same issue with my Coleman Powermate 27 Gallon air compressor. It would not power up under load of the air pump. It would just trip the breaker for that circuit. I removed the belt to see if pump was seized, and was not. I decide to see if the motor would spin at all without the belt, and it worked great. At this point I had already checked my starting Cap to see if it was bad, and it checked out to be fine. So I checked the "points" on the on/off switch inside the regulator, and they were in really bad shape. I lightly touched them up with 220 grit sandpaper and sprayed some contact cleaner on them. After that, it fired right up. I connected the belt, and it fired up perfectly again. I put it all back together, and it's been working great. So if anyone else may have this issue, check the contact points on your on/off switch inside the pressure regulator.
 
 

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