Hi to all, thanks in advance for your help.
I recently found a ’96 S320 with only 47,000 and in pristine condition. My first Mercedes! After driving it for 3 weeks the AC evaporator leaked. The time I was driving it the temperature was in the 90 degree range and only drove 7 miles to work so the “air” was on max. I never had the opportunity to “set” the temperature to a given set point or really learned how the entire HVAC system works. Being a retired mechanic, and refusing to pay $4000 to the MB dealer I performed the work myself. The evaporator, heater core and dryer were replaced. Evacuated the system, filled it, and it worked. So, drove about 400 miles this weekend and found the temperature controls to not work consistently / properly. I had my ac thermometer in the vent, pretty much any setting from 60 degrees to 79 degrees I was getting a temp reading of 40 degrees. When I reached 80 degrees on the selector I finally got heat but little or no ac so the interior heated up pretty quickly. I tried to slowly lower the temp setting to try and find a happy medium but not luck. Ok, I think you have the idea, either hot or cold. Could I have missed something during the install ( o god I hope not) or what is / might be causing this issue.
Thanks, Mike

 

I am new the the forum and not sure how to post but I am experiencing a similar problem with my 1995 S320 LWB. I have owned it for 12 yrs and suddenly having a problem with HVAC. I have temp set at 72. I get intermittant bursts of cool or hot air and hear a clicking coming from vacinity of glove box. Sometimes the AC unit will shut off or jump to the defrost mode and today I had cool air coming from left center vent and hot air coming from right center vent. Hope someone can advise us. I suspect the ACC pushbutton unit is going bad or some sort of valve that switches the air flow. Thanks, Gene