Dodge 2005 Sprinter Cab & Chassis - Manual (Page 120)

120 UNDERSTANDING YOUR INSTRUMENT PANEL
Side Air Vents and Center Air Vents
To open, turn the thumbwheel outwards.
To close, turn the thumbwheel inwards.
Intermediate settings are possible.
Upper Air Vents
The upper air vents supply fresh air (not heated) to the
passenger/load compartment.
To open, turn the thumbwheel forwards.
To close, turn the thumbwheel rearwards.