1992 Mercedes 190 E Heat/ AC problem

Heater/AC does not work on blended temperature. Temp wheel to full heat, gets heat. Temp wheel to full AC, gets AC. Anything in between, like 75 degree setting gets outside air temp. All vacuum cans tested and work. Replaced defective vacuum solenoid manifold. Water valve now opens and closes. Tried a used ($100) climat control switch panel. no change. I can now R&R the dash in my sleep. We won WWII, but the Germans are laughing all the way to the bank on me!

Please Help!


I don’t know enough about your car to give a good answer, try searching and/or posting here:


Not sure of the actual operation but I would look at the lower switch over valve operation. Here are a couple of wiring diagrams. Hope they help.

This is a great resource. Thank you!