Compressor fan motor runs but not the compressor

by Ray
(West Covina, CA)

Hi,
I have:
A Central Pneumatic Model 90234 - 4HP/10 Gallon compressor - about 1 1/2 years old - used occasionally to pump air in the car and bike tires, and some paint spraying. This compressor stays in the garage, and is alway plugged in.

I came home today and the fan on the unit was running. I took off the top cover and the fan motor and compressor cylinder felt really warm. I could not get the compressor to kick on. I tried the shut off switch and the reset switch, but when I turn it on, just the fan runs.

Took the compressor outside and ran a big fan for a half hour to cool it down. Plugged it back in and pulled the on switch. Still nothing but the fan on the back of the unit. Tried adjusting the pressure knob up a bit but it still won't kick on.

The oil level is correct and is never run low. Any suggestions?

_________________________
Bills says...

Ray, there are about eight billion different compressor configurations out there these days (at least it seems that way) and I don't know even a small portion of them.

So tell me, is the fan attached to the shaft that runs through the motor? If so, and the fan is turning, then the motor shaft has to be turning too, right?

If the motor shaft is running, what is it attached to, a sheave? Is that turning?

If it is a direct drive (no sheave and belt) and the motor shaft is turning, then you've got a problem inside the compressor pump itself.

That the fan was running and the compressor pump was hot tells me that your unit was running, and in fact, may have been running a long time without your notice, due, I suspect, to an air leak somewhere.

Check out Duty Cycle linked from the site map page for reasons why this might concern you.

I need more info to try and be more specific.

Tell us all everything that is, or isn't that's supposed to be, happening on your compressors.

Cheers,

Bill




Comments for
Compressor fan motor runs but not the compressor

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Aug 25, 2011
 fan runs but compressor motor not working
by: Anonymous

I have a HotRod dual cylinder type compressor with the same issue, i called the 1-800 # this morning and was told that as long as the fan was running (on my Hotrod one, shaft from fan continues through whole unit as one peice)then the motor is fine, i was told to remove the oil, oil cover on the side opposite the fan end and inside there will be a hex head bolt, it has likely slipped loose from vibration and is a commonn problem in compressors.

So I have not tried it yet as I am at work, but though I would pass this on just in case your is not fixed still and it might help.
May 15, 2011
 Mine, too, was this resolved?
by: matx

I have the same compressor and what appears to be the same problem. In my case, it is not left "active" when not in use. I was texturing the ceiling of a small room when I noticed pressure was dropping, and although I could hear something running, the pump was obviously not.

________

Based on earlier comments, if the shaft running the pump isn't, and the motor shaft is turning, then either the shaft into the pump has failed, or it has stripped the connection so that the shaft turns, but the pump does not.
Jul 30, 2010
 Reply to Bill
by: Ray K

Hi Bill,
thanks for responding.

I checked the compressor and the fan and it does connect to a shaft that runs through the center of the electric motor section. From there is looks like the shaft goes into the bottom of the cylinder part (pump) of the compressor.
When I turn the unit on, the fan and shaft are turning, but not the pump. There is no indication that the pump is working.
The compressor is in my garage and and always plugged in. I don't leave the hose connected to tools or air chucks. It does get hot in there, especially since we've been having 90+ temps the past week.
Possibly the compressor kicked on and was so hot that something let go inside the pump section?

I'll check the link you suggested and see what information I can glean from that.
Any further suggestions are greatly appreciated.

Thanks!
Ray

______________________
I can't see your unit, but does it look like the shaft that's turning the fan is the same one that's going right through the center of the motor and into the pump head?

If it is, and the shaft that's turning the fan isn't turning at the front of the motor, hmmm, you may have a serious motor issue.

Bill

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