Pontiac Sunbird Owner's Manual page 107

Comfort Controls & Audio Systems
Heating
Sliding the upper lever to HTR (Heater)
and the lower lever to the right will send
heated air through the heater ducts, and
some through the defroster vents.
The air conditioner compressor doesn't
run in the VENT and HTR settings.
This reduces engine load, resulting in
improved fuel economy. If either setting
fails to keep you comfortable, or causes
your windows to fog up, slide the upper
lever to one of the A/C positions, or to
DEF (Defrost).
Defrosting
The DEF setting directs most air
through the defroster vents, and some
through the heater ducts.
PJ4001
Defogging Windows with
Air Conditioning System
To Defog the Windshield:
Slide both levers to the far right and
move the fan control lever to HI.
To Defog the Side Windows:
Set the upper lever to B/L (Bi-Level)
and the fan control to
HI.
Aim the side
vents toward the side windows. You can
close the center vents for increased air
flow to the sides.
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