Air Comes Out of Defrost and Floor Vents Only

[mpipes79]

Any replies to last post about AC cut off when control turned to defrost

 

[Martins hemi]

The A/C is needed to dry out the air, otherwise your windshield would fog up.

Nearly all cars work this way

 

[Oliver Closehauf]

On any car I've ever owned, the AC compressor runs when defrost is turned on. It dries out the air and keeps the seals lubed in the compressor extending their lives.

 

[MissouryDude]

I have a 2002 Dodge Ram 2500 Diesel. Had a similar issue with my AC blowing up through my defrost. Turns out it was a vacuum issue. Parts of the vacuum assembly were deteriorated and causing pressure loss.
Ordered a vacuum harness from my local dealership
Part # 55056421AA for 22.35, took me 10 min. to swap out, fixed my issue.