need help with volvo air leak

i would check the main air line at the compressor. it is about half an inch around and metal (usually silver). it has a screw on fitting, and sometimes they come loose. i had one do that and it would only build pressure over 1500 RPMs.

edit: if it is not fixed, it can eventually burn the compressor up as it is constantly running and never gets a chance to cool down.

 

Check the fan hub,air ride bags and valves

 

Turbo actuator we had a cummins that leaked while running, finally figured out it was the acuator but it wouldn't leak with engine off.

 

Ditto on actuator if its Cummins

 

Do you have the trailer brakes set?Leak could be coming from the trailer.Or get some windex and spray start from the steering column where the hoses are and work your way around.look for bubbles.

 

+2 on the Cummins actuator leaking. It will only leak with the engine running, not even with the key on. The only thing I can think of other than that is a leaking fan hub.