northbender42

I have a 93 GKL with the ATC system and i found that my heater will only work on high. I know the problom for that is the reister is bad thats ok for now i got heat on high. My problom is it is stuck on the floor position and when it rains i need to roll down the windows if it fogs up....and i live in seattle ...lol. When i got the fan on high and turn the mode selector and i kneel down and look under the dash on the drivers side i can see the plastic parts move with each selection so i would think the mode sector is working but why wont it move to deffrost or pannel just stays on the floor. I went to heatertreater.com and they said that there was a vacume hose under the pas, side that may get knocked off but i thing that is for a whole vacume control panel and not the ATC system. This is driving me nuts i have looked all over the web and on here and cant find where my problom is an issue. Do the blend doors affect where the air go's i thought thats only for heat and cold mixing maybe i'm wrong......... thanks for any info you guys can give

Allie

I know there's a chance you won't be back to read this, but i have a pretty good idea of what that might be.

There should be a motor somewhere that switches those modes and it's about the same size and power as the blend door motors. Also the panel itself might have issues. If you pull off the panel you should be able to diagnose it with a voltmeter.

But i'll get back to this sometime later when i have time to research... a repair manual would be a nice place to see where all this stuff is located

Allie

P.S. As to why i'm so sure, well, my WJ doesn't always switch modes on time or correctly.... I can hear a motor that does the switching

But don't really care about this, since i can just turn the **** back and forth and it'll get back to normal...WJ's being newer might have a controller chip instead of all-analog stuff, so i won't bother fixing anything...