Mitsubishi LANCER Owner's Manual page 407

Comfort controls
Air selection switch
Normally, use the outside air position to keep the windshield
and side windows clear and to quickly remove fog or frost
from the windshield.
To change the air selection, simply press the air selection
switch. A sound will be made every time you push the switch.
Outside air {Indicator light (A) OFF}
Recirculation air {Indicator light (A) ON}
5
The air selection indicator light (A) shows the selected posi-
tion.
5-8
If the outside air is dusty or contaminated in some way, use the
recirculation position. Switch to the outside air position every
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now and then to keep the windows from fogging up.
CAUTION
!
Using recirculated air for a long time may cause the
windows to fog up.