2013 Cascadia mysterious air problems

Hey guys!
I’m having an issue with a cascadia with the dd13 engine. If you let the truck sit overnight and start it, it will build air pressure until the air dryer pops off at 120 psi. But- after that the compressor will not cut back in and build air until it sits shut off for awhile. I replaced the governor- no change. I replaced the unloader valve (yes- without pulling the compressor- it was miserable) no change. While the unloader was out I sprayed some carb cleaner down the hole to maybe free up a stuck valve in the compressor head. No change. Throw some ideas at me- where would you check next? Thanks in advance!

 

Just to update. I ended up disconnecting the unloader line at the governor with the truck running and lo and behold- it was pressurized. The compressor started pumping as soon as I disconnected the line. Either I replaced a bad governor with a bad new governor, or there is mega moisture in this air system or I got an attack of stupidity when I replaced the governor and put a plug in the exhaust port. I’ll dig into it further and post results, maybe it’ll help somebody out sometime. I’ve got the old girl on the ropes now!

 

Well, I put a plug in the exhaust port of the governor when I changed it. That’s why it was acting up. Removed the plug and everything is normal as far as building air. Nothing like publicly admitting a mistake but a good one for the “I did that once and here’s what happened” file