Air Compressor Question

[M35A2-AZ]

What is the pressure that the air compressor should turn back on?

The problem I am having is that the Air Dryer is popping off a lot.
The truck builds pressure ok and the Air Dryer popes off the at round 120psi and it looks
like the compressor comes back on at about 110psi and builds back to 120psi and the dryer popes off again. All this takes about a one min.

 

[doghead]

Have you serviced your air dryer recently?

 

[M35A2-AZ]

Yes that is the first thing I did.

 

[Suprman]

When you reach governed max pressure, the governor tells the compressor to stop making pressure and it also tells the air dryer to vent its expello valve. Thats how the air dryer purges moisture it has removed from the air. I prefer my governor to be set around 135.

 

[gimpyrobb]

I would think lowering the turn on pressure would be fine, maybe 90psi? I'm sure there is a "spec" for the on and off pressures somewhere.

 

[Suprman]

I dont think the expello valve is adjustable. If you look on the air dryer there are 3 lines going to it. Air in, air out and the air line from the governor. I believe its branched off the unloader air line.

 

[M35A2-AZ]

Grimpyrobb, I do not know how to change the turn on PSI only the turn off psi on the reg.

Suprman, I saw the little line that runs back to the reg. (governor).

 

[gimpyrobb]

I was talking about the air gov that tells the comp to turn on and off.

 

[gimpyrobb]

Whoops posted at the same time. I had a diagram somewhere, let me look.

 

[M35A2-AZ]

Is the expello valve in the compressor head?

 

[gimpyrobb]

http://www.bendix.com/media/documents/products_1/compressorsgovernors_1/troubleshootingguide.pdf

 

[gimpyrobb]

Is the expello valve in the compressor head?

No, its on the air dryer.

 

[M35A2-AZ]

No, its on the air dryer.

OK, I have put a complete new air dryer on the truck and I still have the same problem.
It just looks like the air compressor is coming on to soon.

 

[Suprman]

Try setting your air governor to 130psi.

 

[MtnSnow]

When I first got my truck the air gov was set to about 110-115 psi and had a bunch of issues like you describe. after servicing my dryer and the rest of the system I adjusted my air gov to 130-135 psi and my system is much happier now as well as the CTIS system seems to work better too.

 

[PETE BALLARD]

You should just buy a new air governor, they are so cheap it does not make any sense to fool with them - in the past i have tried to re-adjust them only to replace in a month or so when they revert back to unacceptable antics. Short story- service your air system annaully which should include the air dryer components and governor and you will never be on the side of the road doing the old bypass thing. Also keep in mind that some of the newer emergency and service valves have higher crack pressures so going up to 130-140 is not a bad move. Last air gov that i bought was brand new and cost $21.05


I forgot to mention, check the line going from the compressor to the dryer for leaks, a leaking line will also result in the same situation happening - continous perging.

 

[M35A2-AZ]

Thanks, some good ideas to try.

 

[5ton toys]

psi should be set at 120 high and should turn on at 100 gov can be set at different pressures but high and low will always be 20 psi apart .

 

[quickfarms]

Have you ever done the COLA test on your truck?

It is required to be performed daily.

It checks governor cut in, cut out, low air buzzer and applied brake to check for leaks.

http://nalogistics.com/wp-content/uploads/2014/03/Air-Brake-Check-The-C.O.L.A-Test.pdf

It is all covered on the CDL

 

[M35A2-AZ]

Have you ever done the COLA test on your truck?

It is required to be performed daily.

It checks governor cut in, cut out, low air buzzer and applied brake to check for leaks.

http://nalogistics.com/wp-content/uploads/2014/03/Air-Brake-Check-The-C.O.L.A-Test.pdf

It is all covered on the CDL

Yes I have, It does not lose air and cuts in and out with in limits.
Low buzzer comes in as it should.

Will get a new reg. and try that next.