Engage 4x4 AC turns off. Help

[usmcgriff]

Every time i switch the truck to 4x4low the ac switchs and from the front panel to blowing on the window. this is crazy can any one help

[06F250FX4]

I take it you have shift on the fly 4x4, with the swith on the dash. Sounds like a vacuum problem, as the 4x4 and a/c controls are both controlled by vacuum. Wish I could be more help.

[Drepka]

Thats what I was gonna say. LOL

[07F250]

I had the same problem with my 2000 Excursion. It turned out to be the 4 wheel drive actuator it is located either under the hood or near the front axle. Basically it was leaking and taking the vaccum from the A/C system causing it to change where the air comes out the dash. I know it did not involve removing any of the dash though. As everyone stated it is indeed a vaccum problem, and I had the same exact symptoms as you. Sorry I cant be more specific with where the part is or the name of it, but I had the dealer fix it. It wasnt too costly if I remember. Hope this helps!

[06F250FX4]

Here is a Technical Service Bulletin from Ford that might help you out: 05-17-4***VACUUM PUMP INOPERATIVE OR RUNS CONTINUOUSLY - CLIMATE CONTROL DEFAULTS TO DEFROST MODE