06 D12D Eaton Autoshift Fan running constantly and Air compressor cycles without drop in airpressure

check the blue hose by the air compressor make sure that is not leaking when the air drier is giving it signal. second make sure its not he fan control making the fan kick on have seen it a million times..

 

you dont need means to check its very simple you just need a good known part to swap it out its not only those that will make fan come on sometimes its also the actual ac and heat controller that goes bad, make sure you do not have any codes for fan clutch on engine ecu if none than next step is the controler swap.

 

if you can't figure it out im in carol stream stop by and i can diagnose it for you it will not be something complicated i'm pretty sure specially being that it is d12