M35a3 air problem???

[jcappeljr]

Hey,Hopefully someone can help out.My a3 wont build up air sometimes and it seems to be coming out of the ctis air valve under the bed.you can start it some times and it builds air right up and sometimes it doesnt.The ctis controller above the steering wheel doesnt come on and the screen has something on it sometimes but it isnt readable.When I picked the truck it had a flat tire,I aired it up enough to get going and it seemed to air itself upgoing down the road,All the tires have been holding air.Any help would be appreciated.thanks, john

 

[R Racing]

Hey John is it a steady leak out of the CTIS when it leaks ?

 

[flyxpl]

pull the plug on the back of the CTIS unit on the steering column .

 

[jcappeljr]

Rracing yes it is steady.

 

[jeep-Jeep]

are you sure it is the ctis valve and not the air drier .
a bad drier will make the compressor shut down and not produce air .
It happened to me at a air show this weekend .
a new drier fixed the problem

 

[jcappeljr]

flyxpl what plug? Is it an electrical plug,Iam not near the truck right now to look at it.

 

[jcappeljr]

I am new to thae a3s,I just glanced at it ,it could be the air drier.I forgot these trucks have air driers.

 

[jcappeljr]

jeepjeep where did you get your air drier from?

 

[AceHigh]

My money is on the dryer also. In addition for trouble shooting purposes turn off the air assist steering valve on the firewall, just to make sure it is not the problem. The air assist vents into the air intake I think, and air escaping can do it quietly.

 

[AceHigh]

The air dryer is a Haldex Pureair. Parts are available at big truck stores, including a whole new unit. Erik's has parts for it:

Air Dryer Filter & Small Parts Kit For M35A3, Haldex "Pure Air Plus", DQ6026

 

[jcappeljr]

i can get one from my local commercial truck parts guy.It sounds like the air drier,It puzzles me because it works fine one then it wont build up air the next day.

 

[R Racing]

Yes try to remove the connector from the back of the CTIS up on the steering wheel and see if it still does it. If it does than its your dryer.If not than I would say its your CTIS. I'm thinking dryer as well from what it sounds like.

 

[R Racing]

The dryer valve can get rust particals in them and keep the valve open even when its supose to close .

 

[sierra117]

I believe the valve on the air dryer that releases the moisture from air system is getting stuck open try pushing it in when it leaks. I have had this issue with air dryers driving semis. But keep in mind it might be a temporary fix though. You may need to rebuild or replace the air dryer

 

[jcappeljr]

Also when I turn off the ignition switch it lets out a large release of air,Are they supposed to do that?

 

[sierra117]

They shouldn't they never done that to me my m35a3 has not done that, or any big rigs that I've driven

 

[R Racing]

When the CTIS is pumping up the tires it lets out a big blast andf makes a noise of what sounds like a sick cow lol then it stops for a few min and does it again until all you tires are pumped up . It cycles on when the air pressure is over 90 but can drop to near 60 during the cycle.

 

[jcappeljr]

I guess I am gonig to work on it after work tommorow,Ive been busy painting,now its time to do some wrenching.

 

[R Racing]

Hey John maybe your truck sniffed to many paint fumes !! ​

 

[jcappeljr]

Ha ha,It did this as soon as I picked it up.