Volvo FH13 Air Dryer

Ok I hope there are some mechanics on who could help with diagnoses the air dryer is losing air from the silencer at to bottom with the ignition on but Turn of the ignition and it stops . Is the air dryer goosed

follow 6mm pipe from air dryer to compressor head, remove fitting & clean out carbon from sticking shuttle valve.


Thanks will have a look at the weekend. I have no tools with me

Heater unit goosed just disconnect the heater unit plug.Its to stop the drier purge unit freezing in cold weather

Just keeping peps informed I could find the shuttle valve at the end of the 6mm pipe . Went into Volvo aqnd they replaced the valve attached to the air dryer . Stopped air leaking that day then started again .Anyway went in again it turned out it needed a new compressor head there’s a valve inside that was sticking