My AC is acting up. Most of the cold air is coming out the defrost vents and almost none out of the normal vents. When i accellerate, it gets to where all air is coming out of defrost vents. If i park and shut the controls off and then on, it will work a little better as long as i dont accellerate but even then most comes out the defrost vents. I replaced the control unit but no difference. 1996 Jeep Cherokee Country 2wd 4.0 HO automatic

 

I had almost the same thing happen to a 2000 Dodge ram. Except, when I got on the gas it would force the air back through the dash vents.
I just figured it was a vacuum problem. ie: not enough vacuum to control the ac/heater shutters correctly.
You could check the vacuum canister behind your front bumper (passenger side) and any lines leading to and from it. It could just be a very small leak somewhere in that line.

 

how did you fix it??
Stormy

 

Yup. Vacuum leak.

Can't say about the Cherokee, but most cars will have a vacuum can (looks like a #10 tin can) that is used to store up vacuum so you can accelerate without changing the air flow. And they will also have a one-way air valve so that air only flows one direction.....follow your air hoses; you'll find it.