I have a 2007 cat C 15 just replaced. My air dryer is having problems now I’ve noticed when my compressor goes into neutral it is discharging air out the inlet tube.
Gosh--no one jumped on this-27 hours have gone by and no one helped what's HEF coming too!
I figured it out. It was my uploader valve in my compressor. Had a bad O-ring. Cheap fix.
That's good-thanks for a return post about repair.