Dash AC blows out of the defrost vents
the dash AC blows out of the defrost vents when engine is under a strain, such as climbing up a hill, etc. my motor home is a 2000 itasca suncruiser. the engine is a ford v10 i feel it is a vacuum...
Forum Discussion
The Ford V10 engine does indeed supply vacuum for the HVAC controls as equipped by Ford. On long WOT hills though, as Big Katuna mentioned, the vacuum can drop low enough that the door actuator switches to the fail safe defrost position. As also said, adding an aftermarket electric vacuum can overcome the drop in engine vacuum. The one I added is an aftermarket replacement for the pump Ford uses in their diesel pickups. If there's a coach manufacturer that added a similar pump at build time, I'm not aware of it. I have seen various owner and dealer installed pumps though.
