Originally Posted by Opihi59

Okay, knowing what to look for/look at is helpful, but sadly I have nothing definitive to report. I did manage to get my unit to go to the OFF position but it never started blinking over multiple tries either with key to RUN, or actually starting it. I took several drives of adequate speed and duration to try to "reset" but achieved nothing else. I did get varying outside temps between 82 and 74. On one occasion the off light got very dim, but didn't flash. What happens is that after waiting 20-30 seconds to see if it will flash, engine on or off, the fan will start blowing gently, and putting out air from the defrost vent as well as the foot vents. On some tries, I can hear the compressor kicking on and off, and if it is running the air will be cold. I will let it sit overnight and try again in the morning. It is not making sense at all, and is inconsistent in everything but being broken. I can't make any connection to having removed the neg battery terminal and fixing my instrument cluster, but I cannot help but realize it was working fine before this, and doesn't work now.

I did find this video, wherein the author had non-responsive buttons on his head unit, and repaired it by disassembly, and cleaning contacts with a pencil eraser. I will likely do that tomorrow to make sure that isn't the issue, and it is a simple enough process once you know what to do. This Video
I also got the idea to create a fault code by disconnecting the outside air temp sensor, then running the diagnostic test on it again to see if I can get the OFF light to blink, and then interrogate for code 03, just to see if that mode will function. I was able to press both fan speeds down 5 seconds and get it to display OO, and could scroll up and down thru codes. But on another try following a short drive, it displayed - - Of course none of this is helpful. I'll post back in after I try cleaning contacts on the head unit tomorrow.

(maybe the - - code stands for You're ****ed.)

Originally Posted by sumrtoy

Did this recently. Worked great. Solved my "mind of its own" control unit behavior on my 95. Not sure it will solve yours. But after 20 years, the contact build up residue. And you'll see it as soon as you get it apart.