Ever since I purchased my very clean late-run '86 GT (basically '87 with all '87 factory up-grades,) I've noticed the heat/cooling control damper, makes a loud noise when it opens or closes! Then it started periodically sticking shut, no matter what button I pushed, although the A/C, vent or heat was still operating, just stopped blowing air through the dash diffusers! Whenever I parked the car for a while, it would open on start-up, as long as I pushed a control button before starting the car. It continues to work as long as I don't try to change the setting by pushing a button when driving...then it just closes again...until I shut the car off and let it set awhile, then push a control button before starting the car, and not try to change it or it will close again.
I know it sound crazy, but has anyone ever had this problem, and better yet...how to fix it? Does the heat/cool damper have a servo motor that needs replacing or something??? If so, how do you get to it to fix it?
It is just a cable that controls the door. Ditto on removing the dash to access it. I tried to get to mine two weeks ago and it is a pita with the dash installed. On an unrelated note, my car blows hot all the time and I have checked the door. I don't really see any adjustment in the cable and am considering putting in an external heater core bypass to mitigate the heat in the car on warm days. I will keep an eye on your thread.