Hi guys...this web place is an excellent one! good work...
PLEASE READ THE FOLLOWING...ALL OF IT PLEASE!!!!!!!!!!!!!!!!!!!!!!!!
Now here is the problem I have...
I have a 200E, 1993 Mercedes-Benz, and I have 2 problems with the whole system of heating/cooling...
1) A while back, while I stopped in a traffic light and I was in idle and had the a/c on , the RPM would go so low that my car would go off...I had to either keep the gas pedal down in order to keep it in high RPM and not let it go off, or just turn the A/C off...I fixed that though to a service place (cost me 100 euro)...
but then after a week or so, when I was in low RPM (idle), my car wouldn't go off, but the A/C from cold air, would suddenly bring hot!!! I had to turn the A/C off and then when I was speeding and had high RPM, turn it on again and everything was just fine...so as you can understand I could have cold air coming out only in the freeway and not in traffic!!!
2) I didn't have time to fix that problem and after that, a few weeks later, I had no air at all coming out...but the compressor of the A/C worked fine (I could hear it and feel the cut down of my speed/RPM!)
I read some posts from here about the heater blower and I decided to see what's going on...I just opened the wood trim and took the climate control buttons out (with all the pack with it. plackets, etc...)...I opened up to check the electronic placket in it, in order to see if any line/circuit was blown...but nothing...everything perfect! BUT, on the left and right side of it, there are 2 plug-like connectors...the one is on the left side behind the rolling temperature button, and one on the right side behind the Low, Auto, High buttons...I was "playing" with it, and listen to this!!! when I pulled out the RIGHT plug ONLY (behind the low, auto, high) I had air coming out of it again!!!!!!! both cold air (when I kept the gas pedal down and had high RPM), and hot air!!! but couldn't turn it off or change it from low/auto/high...just had lots of air coming out!!!
I don't know what is wrong with it...I'm thinking any sensors or something?
If you have any ideas PLEASE HELP! (because I took the car to a couple of service stations before I check it myself right now, and without open it up they told me "it's simple...you need the blower thing replaced and it costs around 300 euros + another 200 euros labor!!!"), and I know that's not the problem or else, how did it happen to have air coming out without the right plug in its place???
Thanks for listening guys...your help would be much appreciated!
(thank God, I still have my 1992 Mitsubishi Eclipse GS, and its A/C would make the car an igloo!!! and 11 years now I have NOT spent a cent on it!!! and the car just flies!!! I bought that car in the US back in '92 when I was studying in Texas, and I loved it SO much that I took it with me back home in Greece...and my father has paid his Mercedes twice (if you add all the fixing it needed all the time, since '93) ...should we stick with Japanese cars (made in the USA)? what's wrong with the germans?)
Nick the Greek

Not sure what all is going on with your climate control, but one thing to think about. A lot of cars are set up with full hot defrost as the "default" position for all of the actuators. The idea being, if your system goes kaput, hot defrost (and a clear windshield) would be the most important situation to have. What that means, is that if your vacuum goes away (like REAL low idle), your system goes into this failsafe mode. Same thing can happen if you blow a fuse for the climate control.
My experience with the pushbutton unit has been that the solder joints go bad. I pulled the unit apart on my 123 chasis and resoldered all the connections. Pain getting the thing apart and back together without breaking something, but it did fix my problems.
Not quite sure what to make of the solder joints in MBs. I KNOW they have (had) people there who could solder. My 1956 Telefunken Opus Royale still works and plays beautifully! Then again, they aren't the only ones. GM had a recall on windshield wiper motors for bad joints at the connectors

GUYS LISTEN TO THAT!!!!!!!!!!!!
After I wrote this above (first message) here, I took my car to go get some cigarettes...you won't believe it!!!!!!! I couldn't either!!!
the A/C / heater system works perfectly!!! I can choose the temp, no matter how low or high RPM...I'm telling you it works perfectly!!! Who knows what the hell was wrong with it? I didn't do anything or change anything at all! maybe the 2 plugs I say on the above message had some dirt in them or something, and after pulling them out a couple of times, they got cleaned up or something, and everything is working perfectly!!!
What can I say? Maybe I should "play" a lotto today too! hahaha
If I have more problems, I'll write more...
Nick the Greek