Chrysler Repair: automatic AC-heater 99 LHS, diagnostic mode, refrigerant charge

Question
hey Kevin, long time since the Chrysler forum. The AC on the LHS is not cooling as it should. In the past I would run the recalibration/diagnostic mode on the ATC control head and it showed DTC 23 which is blend air door actuator feedback failure. In spite of this DTC, the AC would be back to working as it should. Last year I replaced the ATC control head due to intermittent display failure. I found a used unit on ebay and it worked well until a few days ago. I noticed it wasn't cooling as well as before and after checking the refrigerant charge I tried to run recalibration/diagnostic mode several times with no success. Do I need to replace the ATC control again or look elsewhere?  Thanks for your help, DaveC

Answer
Hi Dave,
When you try the test does the display begin to blink? If so then it is doing the diagnosis, and at the end it has found no codes. So then I would wonder if the refrigerant level may be low but not so low as to shut off the compressor. If it doesn't display the blinking, then either one of the three buttons that you need to push simultaneously is not making a good contact or the unit no longer will run the test and may need replacement. Test whether each of the three buttons works and then decide which way to go...a new unit, or clean the contacts of the defective button.
Roland