Air Compressor Problems

Any questions about tools or supplies. Post your compressor/gun questions here.

User avatar

Board Moderator
Posts: 9878
Joined: Fri Oct 20, 2006 12:40 pm
Location: ARIZONA
PostPosted: Mon Jun 27, 2022 8:33 pm
The last couple of weeks my air compressor would periodically trip the circuit breaker.

Well today it did it again only this time it wouldn't start back up. So I removed the drive belt and tried the motor. It seemed to spin freely and even for along time after I turned the power back off.

Next I tried to turn the drive wheel on the pump. I could not get it to turn by hand until I drained all the air out of tank. At this point I turned it over slowly and could hear the compressor drawing in air. Oil level is good, air filter is clean, etc.

When I hooked it back up and flipped the power on it didn't sound as loud as usual and then began to periodically slow way down, then speed up.

I recorded a short video on my cell phone so you could hear it, but have no idea how to post it on here.
1968 Coronet R/T


ACTS 16:31

User avatar

Top Contributor
Posts: 2762
Joined: Sun Dec 16, 2012 4:46 am
Location: Canberra
Country:
Australia
PostPosted: Mon Jun 27, 2022 9:25 pm
Sounds like the check valve on the tank inlet is playing up. Blocked or stuck open so there's excessive backpressure coming from the tank, making hard work for the pump.

Remove inspect/clean and refit but I generally find that once they've failed it's better to replace. A faulty unloader can contribute to the problem.
Chris

User avatar

Board Moderator
Posts: 9878
Joined: Fri Oct 20, 2006 12:40 pm
Location: ARIZONA
PostPosted: Mon Jun 27, 2022 11:00 pm
NFT5 wrote:Sounds like the check valve on the tank inlet is playing up. Blocked or stuck open so there's excessive backpressure coming from the tank, making hard work for the pump.

Remove inspect/clean and refit but I generally find that once they've failed it's better to replace. A faulty unloader can contribute to the problem.


Is this the valve near the pressure regulator?
I just downloaded a manual for it, so I will look there as well.
1968 Coronet R/T


ACTS 16:31

User avatar

Top Contributor
Posts: 2762
Joined: Sun Dec 16, 2012 4:46 am
Location: Canberra
Country:
Australia
PostPosted: Tue Jun 28, 2022 1:10 am
It's the one on the inlet to the tank, usually connected to the switch with a smaller copper tube. Can see it in this pic in the middle of the round hole in the mounting plate. If you have one that is electrically activated, rather than pressure, take it off and throw it hard enough that it will land off the coast of Florida.

20220106_131955.jpg
Chris

User avatar

Board Moderator
Posts: 9878
Joined: Fri Oct 20, 2006 12:40 pm
Location: ARIZONA
PostPosted: Tue Jun 28, 2022 1:23 pm
I noticed that air was leaking continuously from the pressure switch area after I shut the compressor down. So, I ordered a new pressure switch and unloader valve.

I will take a look at the tank check valve and may replace it just to be sure.

The compressor is only 15 years old and has been used regularly, so what could possibly be wrong? LOL
1968 Coronet R/T


ACTS 16:31

User avatar

Board Moderator
Posts: 6672
Joined: Tue Feb 24, 2004 7:00 pm
Location: central Ohio
Country:
USA
PostPosted: Tue Jun 28, 2022 2:15 pm
So on our old 7.5 CH we would go through an unloader valve mech. about once every 5 years. It would get like a hard carbon buildup on it that was easier to replace than try to clean. As for the pressure switch.... it was never replaced in the 30 years that I and now my apprentice have owned it.....
Metal, wood, fiberglass, we work it all... www.furniturephysicians.com We can restore the irreplaceable!

User avatar

Top Contributor
Posts: 2762
Joined: Sun Dec 16, 2012 4:46 am
Location: Canberra
Country:
Australia
PostPosted: Tue Jun 28, 2022 8:47 pm
What happens is that the check valve has to deal with air straight out of the pump. It's hot and it's full of moisture plus a bit of oil vapour as well. It's a wonder that they last as long as they do.

Installing a condensing array in between the pump and the tank inlet solves much of this problem. By the time the air gets to the valve it's cooled and dropped the moisture that it was carrying so there's maybe just a smidge of oil vapour left and that, I think, just helps to lubricate the valve and seal.
Chris

User avatar

Board Moderator
Posts: 6672
Joined: Tue Feb 24, 2004 7:00 pm
Location: central Ohio
Country:
USA
PostPosted: Tue Jun 28, 2022 11:40 pm
That makes sense to me....
Metal, wood, fiberglass, we work it all... www.furniturephysicians.com We can restore the irreplaceable!



Top Contributor
Posts: 6213
Joined: Tue Sep 16, 2008 1:17 pm
Location: Pahrump NV.
Country:
USA
PostPosted: Tue Jun 28, 2022 11:58 pm
A lot of the larger single phase motors have two capacitors, One start and one Run Capacitor, Its not unusual for one or the other to go bad.

When you say it slows down when running tells me you may have a Run capacitor that may be looking at the Round bin Grave yard.
Usually if I change one I change both, keep in mind they are probably different capacitance rating so don't mix them up which one goes were! ALSO try to get EXACT replacements if you can.
Dennis B.
A&P Mechanic, FCC General radio Telephone Operator
Line Maintenance A&P Mechanic and MOC Tech specialist.

User avatar

Board Moderator
Posts: 9878
Joined: Fri Oct 20, 2006 12:40 pm
Location: ARIZONA
PostPosted: Wed Jun 29, 2022 11:01 am
Thanks guys, I will check all these potential problems and may just replace everything to be safe.
1968 Coronet R/T


ACTS 16:31
Next

Return to Tools and Supplies

Who is online

Users browsing this forum: No registered users and 52 guests