Air Compressor Help!

[inane2]

Good evening guys,

My vintage 14 gallon Sanborn pump laid down on my this weekend (I'll save that for another thread!) I have a new 60 gallon compressor waiting on me in the corner but I'm in the process of a remodel and haven't gotten to the electric yet as I have no 220.

Picked up a 25 gallon Craftsman Professional over the weekend, sweet CL find. It was bought new in 2010 and has lived a simple life in small garage airing up tires, etc.

The owner was selling it because he said it would often trip his breaker. We started it up, built up to 175 and kicked out. We ran it down to 145 and when it tried to kick back in, the motor locked and hummed. He then showed me he turned the switch off, ran the pressure all the way down, turned the switch back on and the compressor fired up and ran back up to 175 with no problems. I quickly bought it up and headed home.

Once back at the shop, I found that the lowest PSI that it will fire back up is 20 psi.

The compressor uses a common D26613 pressure switch but it costs more than what I give for the compressor.

With it's cover off:

I'm thinking the problem is in the unloader valve itself. It really seems like there's still air on top of the piston when it tries to restart.

After travelling to the end of the internet, I found the valve by itself on eBay:

Craftsman 69D109740 Furnas Hubble Pressure Switch Unloader Valve DeVilbiss | eBay

Do you all think this is the problem? Anyone know of any other compressor parts suppliers?

Thanks!

 

[puckgrinder85]

Its one of the more common issues, not saying its yours. I know ours hisses as it bleeds the air pressure off after shutdown.

 

[SPYDERLK]

. Yes. You dont want pressure on the piston at start. Its bound to be that unloader valve not functioning and letting tank pressure leak back on the compressor.

 

[skyhook]

When it shut's off, do you hear air bleeding out of the valve, if not,
it's most likely that, let us know if you get er fixed.
It could also be dirty, not sure if these can be cleaned.

 

[Gary Fowler]

The pressure regulator went bad on my Craftsman compressor and Sears wanted over $150 for a new one. I found one at Atwoods for less than $20, installed it over a year ago and it is still working fine. Couldn't believe what Sears wanted for that part. I was ready to buy an new compressor rather than pay the price they wanted for a new regulator.
As for your problem, don't ever run a long extension cord to your compressor, there is too much voltage drop even in a 50' cord to allow the compressor to start. Mine has a 6.5 HP rating (yeah right and runs on a 20 amp breaker)and will not start unless plugged directly into the wall socket OR bleed off the pressure to about 20-30 PSI just as you describe.
Try yours directly to a wall outlet and see if it doesn't work. I suppose it could be the valve, but since I saw all that extension cord, I bet that is your problem

 

[Gary Fowler]

ON another note, do you really need 145-175 PSI service? My compressor only runs to 145 before shutoff and I find that it does well for my uses. I think it cuts on at around 50 which is a little low for impact guns but runs everything else ok. I could adjust the on switch higher if needed just as you could adjust the on pressure down a lot to make it easier to start.

 

[inane2]

Thanks for all the replies guys. Mine doesn't sounds as if it's bleeding anything off when it shuts off at 175 psi. I'm going to loosen the fitting at the unloader valve and see if there is any trapped air there. I'm sure I'll end up removing the valve and checking it over.

Thanks Gary. I do have it plugged directly into the wall. The orange cord in the pic is my air hose. I hear ya' on the 175 psi, I don't need that much. It wouldn't hurt my feelings if it dropped a little lower than 145 and then kicked back on.

Thanks again guys, I'll keep everyone posted.

 

[skyhook]

Good luck, inane2...I wish I could have mine set to 175,,
if you can keep it at that, i would, you can always regulate the output.

 

[PILOON]

Most compressors that I have worked on demonstrating the problem described end up having crud in the unloader valve. Often due to water that blocks the opening and or rust.
The style that has a small cable will have the actual valve at the tank while some valves are directly at the base of the pressure switch.

One way to confirm that the unloader valve is the culprit is to dump all the air using the safety valve* and see if the compressor will then re start without stalling and or tripping a breaker.
Some motors use run and start capacitors which might also be the culprit but from your description I vote for the unloader.

* that is located below the one guage and to the left of the other and has the pull ring installed.

 

[nc redneck]

I would consider start capacitor. Also a hard start kit. Very cheap $ 25.00 bucks or so. Available at any electric motor supply place. Used a lot for older AC units to get a few more years out of them.
Good Luck
Scott

Unloader valve should hiss for about 30 seconds after compressor stops running.