Air compressor

[Jasonrkba]

I picked up a lightly used 26 gallon air compressor. I ran a long heavy gauge extension cord to power it up and it ran fine, cut off at about 125 lb but when it needed to crank back up it popped the breaker. I turned it off then flipped the breaker back. Now I turn it on and it starts for a second then humms. Shut it off then bleed it down to about 25lbs, turn it on and it runs fine. Any suggestions?

Thanks. Jason.

 

[ANewSawyer]

Hmmm, I have read what causes that but don't remember what it is! It is on google somewhere.

Try this page: http://fix-my-compressor.com/air-compressor-just-hums/

http://fix-my-compressor.com/air-compressor-just-hums/

 

[Jasonrkba]

Sears direct says change the check valve, that it is stuck open.

Thanks. Jason.

 

[Marshy]

Is the motor 110 or 220 volts? I'd suggest a larger gauge cord and proper breaker size.

 

[mijdirtyjeep]

Mine was doing the same thing when I rebuilt it a few years back. What happened on mine is the little arm that contacts the unloaded valve was not making contact. This kept the air pressure in the line from the piston, and the motor could not overcome the pressure to get spinning up. It is pretty easy to see if it is working or not, and if you have your ear down by it when the pump cycles off, you will hear the air bleed out.

 

[Jasonrkba]

It is 110. I ran a cord Because it's in the basement and we have the old two prong wiring down there. I just didn't feel comfortable cheating it. I do plan on rewiring it (the basement) in the future and the box has already been updated.

Do you think it would pull more amps at startup if the tank is full as apposed to empty?

 

[Ted Jenkins]

Your starter is worn out. Unless you do not have a typical compressor motor. If your motor has a metal cover with a 2 inch bulge then that is your problem. To replace them can be very tricky because the motor is not likely to be like new condition. I have replaced many starters to find out that the motor did not like them. So you may have to experiment a bit to get it just right. When you take the starter out not the run unit but the starter unit it will have a range of resistance so replace with the same range and hope all is well. If it burns up then go to a slightly more resistance unit or slightly less. I every once and awhile I see starter unit on sale so I buy several to have on hand. Thanks

 

[Jasonrkba]

Is that the capacitor?

 

[Ted Jenkins]

Yes sir. Thanks

 

[Jasonrkba]

Makes sense. Do you think the long extension cord could be underpowering it? A quick search looks like the caps are around $40. Just hate to guess and it not work.

 

[Jasonrkba]

Also is this what we are calling unloader valve?

 

[mijdirtyjeep]

The black hose is going to feed the beeder (unloader valve). Trace that hose back to its source. The brass part is the check valve. It keeps air in the tank and allows the unloaded valve to bleed off air in the line without draining the tank

 

[mijdirtyjeep]

This is the location of my unloader valve.

 

[Ted Jenkins]

On my compressor the motor started to act up so my thought was to check the unloader so It got completely disconnected and it made no difference. So I added a hard start capacitor and still had problems. I ran into some one that understood motors better and recommended a higher torque motor which ran so well that I forgot about the unloader and all the other issues. The start units still have to be changed now and then, but not a big deal. I bought an assortment of caps more than 20 of them for $50 including shipping from the Surplus Center awhile back and still have about 15. Like every thing else if you shop around you can find deals, but would never pay more than $5 for a cap since they might work or not. Thanks

 

[Jasonrkba]

I'm guessing one like this. I read that you should short the old one out by crossing the terminals with a screwdriver before removing. How does that discharge it if it still has power stored in it?

 

[mijdirtyjeep]

Have you at least ruled out the unloader valve? All it is, is a tire schader valve. By simply pushing it up with a screw driver or just removing it for a trial you can at least rule that out.

the reason I believe it to be the unloader or check valve as you stated that

Shut it off then bleed it down to about 25lbs, turn it on and it runs fine.

. So it should not be a capacitor problem, or an extension cord problem. Now a hard start capacitor probably can over come a defective unloader valve, so it will cure (mask) the problem as well.

 

[Jasonrkba]

I haven't but I will.
I didn't know much about how compressors worked a week ago but that's sure changing.

Thanks for the help everyone.

 

[Jasonrkba]

Seems it's integrated into the on off switch.

 

[mijdirtyjeep]

need a pic from the top side

 

[Jasonrkba]