I had the car for more than a year now . thiis is my frist merc i love it every one tell me this car year will run for every . well i have a few problems my A/C vent want to work when it want too. i have replaced the contrl unit on the dash it still want to stay in the defrost vent till i drive it for awhile then it will go to dash vents or if i take off slow it will swich to dash vent could it be in the dash and it seem all the buttons on the control dose not do all the fuction i have to hit the button next to the defrost button to get the fan to come on the i can go to ecommy button then i can have fan control over the other button ANY help would be good

Sounds like a vac issue with the vents (leak). Sounds like the motor is going on the fan if you have to get it started with full voltage (defrost button).

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1983 Mercedes 300SD
1987 Mercedes 300SDL
2001 VW Passat 2.8 AWD
2007 OM642 Jeep WK 4x4

that what i thought i have and 82 doge van it did that and it was a one way check vavle that was bad i will look closer to my meany vac line this car has LOL!! i did replace all the plasic line i will look to see if one fell off because