Anybody know anything about car heaters?
 

The heater in my 96 F-250 doesn't work. Well it works just fine but where ever you turn the air control it only comes out of the defrost area but the other controls work just fine. It seems to be vacumn operated but I would have thought that if it had a leak it would leak for all of 'em. I replaced the switch portion from a junkyard one I got off ebay (impossible to find none AC stuff anymore) and it still works the same way. Any ideas out there?

If I remember some heater control units have multiple vacuum lines. i had a older Buick which had this setup and one of the controls would never work but all the others did, come to find out that one of the lines had come loose and wasnt getting full vacuum, I pushed it back on and worked fine after that. Dont know if the late models still use this setup but doesnt hurt to look. Hope this helps :)

Yeah theres like5 back there but no matter if you have it on vent, heat or bi it still comes out the defrost which is what made me think the switch was bad