When I get in and crank up the air all the way with the selector setting on "face", all of it goes straight to the defrost. If I turn it down it will slowly come trrough the vent. Also, if I am driving up hills or gasin' it to get on the interstate, it will go straight to the defrost untill I get off the gas. So my question is: Do you think this would be a vacume problem or the selector shorting out. I'm leaning toward a vacume leak, but the haynes book isn't all that heplful.