water pump replaced/climate control issue
 

1986 300E
I recently replaced the water pump, belt, tensioner, thermostat, and related hoses. When the water pump failed the car got hot but did not boil over. After completing the work I have driven the car over 100 miles and it runs perfectly with the coolant temp reading normal.
However, I have found the climate control not working as it should. When I set the temp to full heat, I get heated air but the slightest adjustment from full heat provides cold air. I'm getting either full hot or full cold with nothing between. Is it possible something happened related to the climate control when the water pump failed?

Classic bad monovalve (insert)symptoms. About 40 some odd $ and 10 minutes should get you back up and working correctly.

Jonathan

Thanks Jonathan, the monovalve is the original and I had suspected it as the source of the problem. Thanks to this forum I know how to repair it and will post results.

Mono Valve
 

There is no repair kit for that valve. You will have to replace the entire unit. Mercedes part number 000 830 72 84.

Indeed...sorry, my mind defaults to 126's/117's..

You might try taking it apart, giving it a good cleaning..always worth a shot before dropping 100+ on the part.

Or you could replace it w/ a plumbers valve if you want to go old school;-)


Jonathan