Rear air acts funny after battery disconnect.

[olliec420]

A while back I disconnected battery for something and noticed the rear air was coming out of the vents by the rear evaporator. After a week or so it started working normal again. I also noticed that the DIC outside temperature reading was wrong for awhile too.

Fast forward, I just had it in for trans rebuild. They disconnected the battery of course. Since I had it back (like 2 weeks) its doing it again it hasn't gotten right yet. Does anyone know why its doing that. I dont mind waiting til it gets right but I'd like to know why.

 

[BG1988]

the outside air temp sensor is bad if it has an incorrect reading the a/c will not work

 

[olliec420]

the outside air temp sensor is bad if it has an incorrect reading the a/c will not work

Yeah that's what I thought last time it did this and I replaced it and it didnt fix but then everything got right on its own shortly after. This morning, now a couple weeks out, the rear a/c is still blowing out of the rear condenser only. Blowing the proper speed and temp but not out of the roof vents where I want it. Manually changing it does nothing. The outside air temp on the dash is displaying correctly now. So weird.

 

[mikez71]

flapper door motors going out? (air diverter/blend doors whatever they're called)

 

[olliec420]

flapper door motors going out? (air diverter/blend doors whatever they're called)

I thought about that but they worked fine all winter in FL. Changing between ceiling and floor vents. Then they disconnect the battery and things are weird. And same when I did it last summer. Other than that no problems with switching modes. The weirdness on the ambient air temp is goofy too.

 

[Sam Harris]

There’s a relearn you can do.. for the GMT800, you basically pull the HVAC fuse, and go through some key cycles.. I’m sure there’s an easy relearn for yours as well.

Maybe try this: https://www.justanswer.com/gm/71pij-reset-climate-control-module-unhooked-batery.html