I have a 1994 GMC Safari Van, when driving down the road with the AC on, on the level it blows fine out of the vents, but when starting up an incline it acts like the blower switches to the floor as I can feel cold air on the floor. Once the van levels out and runs normal again it comes back to the vents. I was told by a good friend that the Chevy's and GMC's just do that, but it sounds like a vacuum leak to me.
Any ideas, anyone else have this problem??
thanks