Buick 1993 Skylark Owner's Manual page 122

BIL (Bi-level)
Windshield Defrost
This setting allows the outside air to flow through your
Buick in two ways. Cooler air is directed to the upper
portion of your body through the vent outlets. Slightly
warmer air
is
directed through the heater ducts and
defroster outlets.
Vent
Using vent will allow outside air to flow through the
instrument panel outlets. Set the temperature knob as
desired.
Heater
On days when it's cold outside, this setting sends heated
air through the heater ducts and the windshield defroster
outlets. If you have the engine block heater, you can use
it in
cold weather (+2OoF/-8 O C or lower) to heat your
vehicle's passenger area quicker. The engine block
heater warms the engine coolant which will ultimately
warm the passenger area more efficiently.
(
See "Engine
Block Heater" in the Index.)
Blend
This setting divides the air flow equally between the
heater and the defroster outlets.
This setting operates the defroster. Most of the air come
out near the windshield. Use defrost when you get fog or
ice on the windshield.
Rear Window Defogger (Option)
The lines you see on the
rear window warm the
glass. Press the button to
start warming your
.window. Pressing the
button again will shut it off
If you turn the rear defogger on while driving at or
above 45 mph (72 km/h), it will stay on as long as that
speed is maintained. You must press the button to shut
it off.
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