coincidentally, I worked on mine today.
I stuck a new Mode Door Actuator as described earlier. I also got a "refurbished" ATC, just so I know I have a known good unit. Still have the code 24! I have been running without the MDA plugged in and still, the only code I get is 24. The situation has gotten worse, the temperature seems to not work properly. The temp seems to go cool until you turn it up to 80 then it gets warm. But there is no real pattern, sometimes it works. I had the cooling system checked out, filled and burped.
I am wondering if the Body Control Module (BCM) is bad. I have been disconnecting the battery while I do work on the ATC /MDA. I do not reattach it until everything is plugged back in.
Anyone have any input? I am at a impasse. Fix it, - dealer-$500 ~ $1000? Sell it, My wife needs a warm car, but she really likes this car.