Thanks for you replys. The temperature slider control has Min and Max markings on the ends of the control, with blue marks in between that increase in width as they get toward the Max end. There is a small snowflake on the Min end and a large snowflake on the Max. I believe the temperature slider control should function somewhat like the thumbwheel temp degree control on automatic systems. I don't believe Mercedes would mark this slider control in such a meticulous manner if did not control something, it may be possible that the dealer did a shortcut installation and did not enable this slider control to function properly. All of the repair shops here are well below American standards and we all have many horror stories, that is why I use this forum for answers to simple questions that could be answered in minutes if my car was in the US. I have used the search many times on this forum and have always found an answer or at least a hint in the right direction.
1987 190 Euro