Air compressor runs but no air pressure

Air compressor runs but no air pressure - Printable Version

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Air compressor runs but no air pressure - bikestuff - 10-07-2014

Gang,

I have read this thread regarding air compressor problems but have not found my solution Air Compressor Problems

My compressor runs, but does not seem to put air into the system.

Symptoms:

1) Air compressor runs but does not pump up tank.
2) With 120V air compressor "ON" I can completely run out of air overnight.
3) Engine can "pump up" system in a few minutes.
4) The 120V compressor runs for a long time but *does* turn off eventually. (It does not feel hot).
5) If I put my thumb over the outgoing air from the compressor I can feel pressure and hear the pump load up. I let go of thumb and can feel a little air and the pump unloads.
6) If I pull wires from the head pressure relief solenoid with pump running, air is vented from the port. (No air vented with wires attached)

I took the check valve out and blew on one end and then the other. It lets air go in only one direction.

I have included pictures along with a diagram of the connections. Any ideas?

ps. On a side note, is there a problem with using 1/4" and 3/8" tubing? It seems as if the 1/4" would restrict air flow.

Thanks,
bill

RE: Air compressor runs but no air pressure - bikestuff - 10-07-2014

I am not at the coach right now, but I am thinking that maybe the compressor is not putting out sufficient pressure. If I hook up an air gauge to the output of the compressor, what kind of pressure should I see?

RE: Air compressor runs but no air pressure - 77newell - 10-07-2014

Bill: first let's make sure there isn't a leak that is nearly equal to the output of the 120vac pump. You say the engine pump will bring up pressure quickly. Once pressure is up, how fast does it leak down. If fairly fast (highly technical scientific terms) you have a leak that needs fixing. If it drops slowly then you most likely have a supply problem.

If you can make a direct air connection between the pump and the pressure switch, also eliminating the tank, you can then fire up the pump and see if it reaches shutoff pressure and, if it does, how long before it kicks in again. If it kicks in fairly (that scientific word again) then the valves in the pump are having a problem. If it behaves well, then you need to go through the peices you bypassed and find the one that's restricting flow.

Another way to get a very rough measure of what the pump is doing is to measure amps to the motor and compare that to any data on pump performance that's available. Low amps would indicate the pump ain't apumpin.

Hope this helps

RE: Air compressor runs but no air pressure - ccjohnson - 10-07-2014

Possibly an issue with the leveling system solenoid valves. If system is airing up with engine on, is it in "travel" mode or level mode?
Does it make a difference which mode as to how fast system builds air pressure? If it turns out to be compressor get a new one from Grainger with 2 yr extended warranty. They recently sent me a replacement "no questions asked" and did not want the old one returned. Very good experiences with them.

RE: Air compressor runs but no air pressure - bikestuff - 10-07-2014

When I air up system from engine, I am in travel mode. The air leaks slowly, (hours vs minutes) either in travel mode or auto-level mode. (As far as I can tell)

Does anyone know how much air pressure I should be getting out of pump?

I replaced pump when I got the coach for general purposes and still have the old one.

Thanks!

RE: Air compressor runs but no air pressure - ccjohnson - 10-07-2014

The Gast should be putting out at least 90 psi. That is what the shut off switch should be set at.

RE: Air compressor runs but no air pressure - bikestuff - 10-07-2014

Ok, So plan is to see how much air the compressor puts out...then work my way to the tank to see where the blockage (if that is the case is). thanks!

Has anyone mounted a permanent air gauge in the front bay?

RE: Air compressor runs but no air pressure - Chester Stone - 10-07-2014

Bill, I am not sure, but I believe the "spitter" filter should be before the check valve. I recall that the check valve is between the tank and the spitter filter. Otherwise I do not think it will work. This may be a problem with the drawing and not your system, and you must have a leak. Do you have the ultra sound system that detects leaks the ear cannot hear?

RE: Air compressor runs but no air pressure - encantotom - 10-07-2014

what i did on my 90 was put a airchuck outlet by the gast compressor then used a gauge i put an airchuck on. you could for sure also easily put a permanent one in

tom

RE: Air compressor runs but no air pressure - Richard - 10-07-2014

Yep, start simple before you rebuild the entire air system. Just put a gauge on the outlet of the pump. Turn the pump on. If and when it gets to 100 psig, turn it off. If it doesn't build 100 psig then you found your problem. If it does, then start looking downstream. A leak large enough that the pump will not keep up is large enough to hear.