hi. i have a question i was wondering if anyone here know how to stop the outside air from entering the cabin on my 1993 mercedes 190e 2.6, the air is cold from center vents but blowing warm outside air from side vents. (not coming from heater valve its working good i check it out first, thanks for the help guys.

You have to manually close the center vents to stop cold air coming in. The way the 190e climate control is designed, you can't get hot air from center vents. Only cold.

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CENSORED due to not family friendly words