Heat/Air Control

99 Bravada with climate control

I am having an issue with my temp setting for my heat/air. When I move it to heat, sometimes it will heat and sometimes it just blows cool or warm, sometimes when I move it to cool it will blow heat. I thinks its either the temp controller or the door that opens/closes near the heater corel. I think that door that opens/closes is directly behind the dash and could suck to get to for me to check it. All other controls work great (fan speed and vent,defrost position)

Which one of these would most likely be the problem child?

My antifreeze is full and I blew out the heater core with air (which nothing came out of but antifreeze)

Truck runs fine so I dont think it has a vaccum leak.

Thanks a bunch

There is a good post here about a 98 blend door fix (with pictures and the common problem), not really sure if it's applicable to a 99 but check it out.
http://www.automotiveforums.com/vbulletin/showthread.php?t=574779&highlight=blend+door

What is wrong with my car's heating/air control system?

There is a good post here about a 98 blend door fix (with pictures and the common problem), not really sure if it's applicable to a 99 but check it out.
http://www.automotiveforums.com/vbulletin/showthread.php?t=574779&highlight=blend+door




Thanks so much, I will try and tackle it this weekend.