Volvo 2001 S80 Operation And Care Manual page 24

Air flow
The air that is drawn into the passenger compartment is distributed from 14 ventilation points.
Air vents in door pillars
A Closed
B Open
C Horizontal air flow
D Vertical air flow
Direct the air vents toward the rear side windows to demist.
Direct the air vents toward the rear seat for the best heating/cooling effect.
pg. 41 Electronic Climate Control (ECC)