Splitter stuck

I have a 2015 cascadia with a dd15 and a 10 speed eaton. I had the same problem last night. When I was on the high side no problem. Couldnt get it to split back into the low side. When it was in the low side there was an air leak on top of the transmission. When it was on the hugh side no air leak. I had a broken airline Right at the fitting where it goes into the transmission. See pic of the two airlines one is red the other is blue. Mechanic Put a new fitting on and off I went.

 

Air solenoid.
It's on bottom of the coolant reservoir. Metal tube with air lines on each end. $150 part I thinks.

 

Pull air line off top of fan clutch and see if you’re getting air. No air, and your clutch stays engaged all the time.

 

You should be getting 12V to the fan solenoid when the fan should be disengaged. But I'd bet on a airline blockage after the tranny trouble.

 

Most trucks have a pressure protection valve. Typically 60-90 psi range. Air brakes get priority. Once tank pressure overcomes the setting of that priority valve, air will be available to air accessories like air suspension, air ride cab, diff locks, transmission, horn, PTO etc.

 

You can disable the air line going to the fan and your fan won’t come on at all. Would more than likely be fine in this weather, until you could get a proper fix.

I had a fan clutch go out in the middle of summer, as long as you kept moving and didn’t pull it too hard on the hills, temp stayed ok. Was able to make it about 100 miles of interstate like that.