Buick 2008 Lucerne Owner's Manual page 160

Operation
(
(Off): Turn the left knob to this position to turn the
climate control system off. Outside air still enters the
vehicle and is directed to the floor. The airflow direction
and temperature can be adjusted, as indicated below.
9
(Fan): Turn the left knob clockwise or
counterclockwise to increase or decrease the fan speed.
The fan speed is temporarily reduced between the
transition to a new mode. The fan will resume when the
new mode is complete.
If the airflow seems low when the fan speed is at the
highest setting, the passenger compartment air filter may
need to be replaced. For more information, see
Passenger Compartment Air Filter on page 3-30 and
Scheduled Maintenance on page 6-4.
Temperature Control: Turn the center knob clockwise
or counterclockwise to warm or cool the air coming
through the outlets.
Mode Control: Turn the right knob clockwise or
counterclockwise to change the airflow direction.
H
(Vent): This mode directs outside air to the
instrument panel outlets.
3-22
)
(Bi-Level): This mode splits the air between the
instrument panel outlets and the floor outlets. Slightly
cooler air is directed to the instrument panel outlets and
warmer air is directed to the floor outlets.
6
(Floor): This mode automatically uses outside air
and directs most to the floor outlets. Some air is directed
toward the side window outlets and to the windshield.
If recirculation is selected while in this mode, it stays on
for three minutes to reduce windshield fogging.
h
(Recirculation): Press this button to recirculate
cabin air through the vehicle. An indicator light below the
button comes on to show that this mode is activated.
This mode can be used to prevent outside air and odors
from entering the vehicle or to help cool the air inside
the vehicle more quickly. This mode cannot be selected
while in the defog or defrost modes. If you try to
select the recirculation mode, the indicator light flashes
three times and turns off.
Operation in this mode during periods of high humidity
and cool outside temperatures may result in increased
window fogging. If window fogging is experienced, select
the defrost mode.