Well my 96 c220 has been flawless not one issue until recently the AC, the AC temp will not go under 59 degrees (meat thermometer in center vent). I pulled these codes from AC controller 233, 416,417,419, 421 and reset them to see what ones may come back. I did remove the plug on the duo valve and heard them clicking when the plug was re-attached.....Any help would be great its hot out and I do love the car. I was considering taking apart the Duo valve and seeing if something is gummed up to start.....Any guidance would be great. Thank you.