The dial acts independently of the electronic system and controls the airflow out of the upper vents on the dash.

The reason for this is so that you can have the heat on in the winter, yet have nice cool fresh air in your face to reduce fatigue and just make it comfy. Same deal in the summer, you can have heat coming out on a cool night with the windows down without heating up the rest of the cabin.

I think it is an awesome feature.

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12 X5 M - 06 X5 4.8iS - 03 X5 4.4i - 03 M5 - 02 X5 4.6is - 99 M3 Dinan S3 - 98 M3 - 92 850i-6 - 92 850i - 91 325ix - 89 M3 2.5 - and a few parts cars