We have a 2004 Peterbilt 379 C15 CAT it won't build up air pressure when it's idling, you have to hold it at 1400 RPM's for it to build up. And once it does build up and you shut the truck off the air pressure don't seem to drop. Put a new compressor on and this didn't fix it. New governor, 2 new main steel braided lines. Any ideas??
Air dryer. It's the only thing left after making sure nothing's obstructing the incoming air supply (like a foreign object or a hose with a collapsed inner lining).
I hadn't thought of a collapsed line. That makes sense too. My last resort was spending another $500> on a dryer. But if that is the problem that's fine. Just wanted all other options. Thanks
Check air intake plumbing to compressor for blockage. Bypass air dryer for testing (connect the 2 large lines together) Disconnect and plug signal line to air dryer (small line from unloader port of air governor) to be sure air from dryer isn't being sent back to unloader valves.
There is a line running from your airtank to your air governor that should kick in the compressor. I had one of these plug up with moisture and oil from a worn out compressor and do the same thing to my new compressor.
Check the turbo acuator, mine did the exact same thing drove me nuts. Found it and replaced it no more problems
