Air dryer cycling too often ?

[Dog_Trainer]

I noticed my Air dryer for my compressor was cycling often on our last trip. When I drained the air off both holding tanks before and during the trip I did not notice any moisture. When I say Often the dryer seems to be cycling about every 30 seconds or less. This is evidenced by the air noise of the blow off valve. My air stays pretty steady at about 150 lbs both tanks when running. No noticed leaks and both tanks have pressure from overnight. I did put new filter media in it a while back but maybe time to service it again. Maybe the air compressor is staying on too long. Any information is always appreciated.

[mtrumpet]

I don't know what air dryer System you have on your rig, but here's a link to the Meritor Wabco web page which will get you to all of their technical literature and troubleshooting guides which may at least help to point you in a direction to find the cause of your problem.

Meritor Wabco

ON EDIT: Sorry, I couldn't get the link to go directly to the literature page, so the above link will take you their main page. Just click on the "Literature" tab, then click on "Air Dryers".

150 psi is high for the air system. Shouldn't be running higher than 120/125 psi max, regardless of which system is used on your chassis.

Just off the top of my head, I'm thinking that the problem may be with either the air governor or pressure relief valve at the air dryer. However, as Brett Wolfe mentioned, the wisest place to start would be with your chassis manufacturer for the most accurate information. They most likely would have an idea as to what the problem may be.

[wallynm]

Air dryer could need servicing.

[wolfe10]

OP,

Contact your chassis maker with your VIN. They can tell you the correct PSI range for your air system.

If it is incorrect, most air governors are easily adjustable.

[Dog_Trainer]

deandec wrote:
Depending on the Air Dryer, the purge valve can be serviced with a kit of parts (about $35) and a few minutes under the rig.

It is basically a new valve, three bolts, with O Rings for a Bendix AD-9.

The 150 PSI seems high. Mine is barely to 120psi. Most are at 125PSI. Perhaps there is a gauge problem.

Thanks for the input I do not know about the pressure I guess it just never occurred to me that it could be too high. It has a gauge for the front and rear air both come up to 150 and have been that way all the time I have owned it. I will see if I have a service manual for the compressor and dryer. It is a bendix dryer I bought a service kit a couple of years ago and changed the media, oring and bleeder valve just as a PM issue. I don't think it will be too hard to get it straight just wanted all the info I could get going in.

[deandec]

Depending on the Air Dryer, the purge valve can be serviced with a kit of parts (about $35) and a few minutes under the rig.

It is basically a new valve, three bolts, with O Rings for a Bendix AD-9.

The 150 PSI seems high. Mine is barely to 120psi. Most are at 125PSI. Perhaps there is a gauge problem.

[CT_WANDERER]

Might be a check valve near the air drier and the drain valve that is leaking. Letting the air pressure fall requiring the air governor to turn the compressor back on too soon. Gary

[Dog_Trainer]

JR45 wrote:
x2 150lbs to high, should be around 120-125psi
JR

It has been 150 since I owned it 10 years ago

[JR45]

x2 150lbs to high, should be around 120-125psi
JR

[Born_To_Travel]

The spitter valve is activated when your air pressure peaks and the compressor shuts off.. Do you have a air leak that is causing the pump to kick on and off?.. Block the wheels and take the parking brake off and with the air pressure up do a walk around and listen for leaks..

[dons2346]

150 sounds a little high. Most run about 125 so you might want to take a look at the compressor governor.

When was the last time you serviced the dryer?