a/c control buttons
 

I have a 190 e 2.3 1987.

The a/c works only when the defrost button is depressed, what do you think is hould do so that the a/c button wil work.I was thinking about replacing the climate controll panel.
Your thoughts?

On the right side of the pushbutton controller are three verticly arranged buttons. The top one is the one to use for maximum AC. it has an icon that is the same as defrost but it is not. Something was lost in the translation because the only similarity to defrost is that in that position the mode door potentiometer is ignored.

The middle button which says AC (I think) won't turn on the AC till the mode door is closed as witnessed by the proper return voltage from the feedback potentiometer.

The actual defrost button is all the way to the left (I think) and will also open the water valve and go hiblow. The air will come out the top ducts not the facia and it will be heated dehumified air.

I always set these cars to max AC by pushing the top vertcal button right side.

Steve i appreciate your precise analysis
 

I see that you are very much knowledgeable in troubleshooting many issue with the mercedez benz.
I look forward to getting a response from you.
I think what you are saying is righton point.
Well is the button that is marked a/c suppose to work at all and if so how?

If the senario is as I stated and you are having problems in the middle button position, then you have either a vacuum problem that keeps the mode door open or the mode door potentiometer is broke or misadjusted. Dealing with the mode door or potentiometer will require a technician or a lot of research.

Here in Florida its easy, just use the top,"Max AC" button, who needs mixed temperatures, we just go for the cold.

Thanks again
 

I wont worry about it. You are the GREATEST.

Stevebfl.

I have a 91 190E and the a/c heater blower stays on high speed, no matter where you set it. What could be the problem there?