Honda 1990 Accord Sedan Owner's Manual page 40

Dash Vents
The corner vents can be used for flow-through ventilation, or
during the heating and air conditioning operation.
The corner and center vents can be tilted up or down, and their
louvers turned right or left, to change the direction of air flow.
The amount of air flow from the corner and center vents can
be regulated by the control located beside each vent.
SIDE
DEFROSTER
VENT
Open
HALF
Close
DASH
CORNER
VENT
CENTER VENTS
WINDSHIELD
DEFROSTER
VENT
Open
HALF
SIDE
Close
DEFROSTER
VENT
Open
HALF
Close
DASH
CORNER
VENT
(cont'd)