Pontiac 1998 Grand Prix Owner's Manual page 167

Heating
Ventilation System
On cold days
use LOWER.
The system will bring in
outside
air,
heat it and send it to the floor ducts.
If your vehicle has an engine coolant heater, you can use
it to help your system provide warm
air faster when it's
cold outside 0°F (-
18°C) or lower. An engine coolant
heater warms the coolant your engine and heating
system uses to provide heat. See "Engine Coolant
Heater" in the Index.
Ventilation
For mild, outside temperatures when little heating or
cooling is needed, use UPPER with the A/C button
off,
to direct outside air
through your vehicle. Your vehicle
also has the flow-through ventilation system described
later in this section.
Defogging and Defrosting
Your system
has two
settings for clearing
the
front and
side windows. To defrost the windows quickly, use DEE
To warm passengers while keeping the windows clean,
use DEFOG.
Adjust the direction of airflow by moving the
louvered vents.
Your vehicle's flow-through ventilation system supplies
outside air into the vehicle when it is moving. Outside
air will also enter the vehicle when the air conditioning
fan is running.
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