Originally Posted by Mountain Gnome
My guess is that the fan is powered by the PS pump, or maybe the motor oil pump, but not its own. Good question that I should know....
Well as it turns out there's a honking big hydraulic pump attached to the back of the air compressor. (Flagged down a diesel mechanic who was checking out another bus).
It runs the radiator fan, the power steering, and maybe a couple of other things. At least now I understand enough to get a CDL B license.
Come to think of it, it could be the motor oil pump.....
(Mostly I want the license so I know what the heck I'm doing driving a 30,000# vehicle.)