Found online that folks say you can hold down buttons on AC module for it to go into diagnostic mode. Anybody out there know if this is true?
AS shown by others; yes - it's true, there is a self diagnostic test.
If you're only getting hot air, regardless of desired setting, then the BDA (blend door actuator) is bad. Not uncommon on the Panther cars. Not really "hard" to fix, but a long, tedious task. Have to pull the entire dash panel (the whole thing, not just the facia bits on the front) away from the chassis a bit to reach it. I did mine and successfully was able to do it in a few hours with help of a friend. There are many vids on this; watch several and you'll get the idea.