'03 F-250 A/C switched to Defrost when 4x4 engaged

[Dan_wcIN®™©]

WTG. I'm out looking at crops today in my fairly new to me '03 F-250 w/electronic switch deal that engages 4x4. No weight on the back so back wheels spin out on (I guess) some coon grawlix. So I rotate the 4x4 switch and move on. Then I notice there is no longer a nice cool breeze blowing at me. The air is all coming out the Defrost. Noticeable comfort change when the heat index is around 115. Only way I found to change air flow back to Vents from defrost restart to truck WTG. Who's bright idea at Ford was that? They don't think I need grawlix cold air blow at me when I'm in 4x4?

Oh WTG =what the grawlix.

[sandbox]

I'm strictly a shadetree mechanic. And most of the shadetrees consider that an insult.

I don't think that is a Ford design feature. If you have auto 4x4 the system uses vacuum to engage the 4x4.

Here is a link to a fella who had a similar problem:

www.powerstroke.org/forum/6-0l-problems-forum/38473-4x4-defrost.html

Don't know if you run diesel but it could be the same problem, regardless.

Good luck.

[Dan_wcIN®™©]

Thanks, Looks like you have pointed me in the right direction to correct this.

[semosandfarmer]

Mine was doing this bad too, there is some kind of vacuum module on the passenger side fender just ahead of the vacuum pump. I finally discovered that the module had an internal leak and plugged it off to fix the leak and that fixed my vent problem. My 4-low hasn't worked for awhile and still doesn't so my best guess is that the module kicks the 4wd Low in but I don't really know, it's the only thing on the truck that's vacuum related that doesn't work.

Other problems can be leaky hubs bypassing vacuum from what I've heard.

[SMASH]

my '02 did the same the other day. but after about 10 seconds it went back to blowing out the dash. switched the knob several times (do to this post) did it every time.