Hello, i just bought a 1999 c230k, besides my current problem
im loving the car!!!!

ok, one side of my vents is cold air, the other side is hot air.
BUT both dials are on blue(assuming blue means cold).

any thought?
thanks

t t t .

My Range Rover has dual-zone auto cc like your car. And it does the SAME thing! Not fun in the summer, we shut off that side vents. The reason why it does it in the Rover is a thing called "blends" motors, which your car probably has as well. These motors regulate the internal flaps in the heater box and cooling ventilation system. When you set it on cold (on my car you actually set the temp) it should close the flaps on the heater and open the one for the air. It isn't, and thus the hot air. These blend motors also control the flow of air, like to the floor, vents, rear, defrost, etc. Make sure all of those settings work correctly. You can try switching from hot to cold a few times to see if you can get a stuck flap free. Does your car have pollen or charcoal filters? On my Rover they say dirty filters is the number one cause of getting the flaps to fail. I know the job is horrible to change on the Rover, probably the same for you.

Good luck

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2002 Mercedes-Benz E320 4Matic
1995 Mercedes-Benz E320 Wagon
2005 Land Rover LR3 V8 SE
1999 Audi A8 4.2L quattro

Troverman, thank you for the suggestion. I will certainly try to 'unflap' lol
a vent ot two!