What do those hot-cold knobs between the air vents do?
Today, I drove my car (2009 328 XDrive) on a highway for about 150 miles. On a cruise control, so I was resting my right shin on the center divider between the 2 front seats. After a while, I noticed that the side of the divider was getting unpleasantly hot (naturally, the heat was on). I called the BMW service, and I was told that this is quite normal, because heat pipes go through the divider to the rear seats.
The technician told me to simply turn the rotating knob between the two air vents in the rear seats all the way to cold (i.e. blue) position. As best as I understood the explanation - if the knob is in the hot (red) position, then the hot air is sent back through the divider, which contributes to overheating.
Naturally, I did that, but I'd still like to know - what exactly do those two hot-cold knobs do (the other one is in the front seat center panel)? What would happen if I turn the knob(s) to the "cold" position in winter? Hot position in summer?
Thank you very much for any explanation!!
Last edited by Razorback1; 11-15-2013 at 01:43 PM.