Central vents, blue control wheel?

[ChrisPidwell]

On my E270CDI Avant, W211, there is a central roller switch with divisions of blue on it.

The manual says its the cold air vent roller? What does this mean? I have tried the a/c on and off and both settings with this roller switch fully up and down. There seems to be no difference?

Any suggestions?

 

[television]

Is not the top center vent always the cold fresh air coming in only

 

[ChrisPidwell]

So when on, it allows codl fresh air in through any vent that happens to be open?

By the way. Re an earlier post regarding suspension low ride height warning. The car was fully loaded with camping gear, no more room on top or in car. I mean fully loaded. Handled fantastically, pulled really well, no blip alarms going off. suspension raised itself nicely when ignition switched on. Just one blip when I went over a speed beep swuare on, all four wheels.

 

[television]

So when on, it allows codl fresh air in through any vent that happens to be open?

By the way. Re an earlier post regarding suspension low ride height warning. The car was fully loaded with camping gear, no more room on top or in car. I mean fully loaded. Handled fantastically, pulled really well, no blip alarms going off. suspension raised itself nicely when ignition switched on. Just one blip when I went over a speed beep swuare on, all four wheels.

Thanks for the update