[justin in time stroker]

need help with my ac, the ac will only blow out of the defrost. Ive checked the vacum lines twice, and when i move the lever on the blinder under the dash by passenger floor board it will blow out of the vents:dunno:. Also when i move the slector to defrost the compressor is still engaged along when on mix???????? Any help will be great.

Truck is a 92 7.3idi 5SPD with banks turbo,4x4 single cab.

 

[justin in time stroker]

well now today it all of a sudden started to blow out of the vents then back to defrost. Also the brake petal is stiff as can be, would this be the vacume pump???????? Someone please chime in

 

[Ol' Smoky]

Yes this may be the vacumn pump. It could also be as simple as a belt too loose if you have a v-belt system. You should also check your vacumn resivoir, the coffee can on your passenger side fender. If its full of rust holes you'll be losing some vacumn pressure from there. As far as the compressor goes, it is suppossed to engage on defrost, your ac system removes moisture to help keep your windsheild from fogging up.