Sleeper air bags

[Rawze]

On my prostar, things like the cab air bags, etc .. are on a line, fed by a solenoid, that only gives pressure when both tanks are above 90 psi...

It could be that the solenoid, or the solenoid distribution block itself is weak or going bad, not allowing full pressure thru it.

Those distribution blocks are also plastic and tend to go bad about every 6 or so years .. especially up north where ice builds up in them and cracks them, making all of the out pressures weak.
http://rawze.com/forums/showthread.php?t...75#pid3975


It is hard to tell if that block is leaking because it will stop leaking as soon as one of the tanks drops below 90 psi.. and all the faint hissing stops. Someone has to run the truck and build the air all the way up to 125+ psi for both tanks.. then turn the key-switch off.. only barely long enough that the engine stops running, then right back into the on position, so that all the systems stay active without the engine turning. Then jump out real quick and listen for hissing, air leaks, etc. right away before the air bleeds off down to 90-psi.

It can be the fan clutch leaking.. the distribution block for the solenoids.. an air bag, a valve, hose.. etc.etc.etc. - Leaks that cannot be heard while the engine is running, and that only happen above 90 psi.

Also if your air-dryer-regulator is going bad, you will get less pressure than 90 psi. Air dryer-regulator is cheap compared to the compressor or that block.. so that is the thing to replace first if it is more than 5 or 6 years old, along with checking for leaks like mentioned above.