Geo 1995 Prizm Owner's Manual page 110

Rear Window Defogger (Option)
remove fog from
the rear window.
Press the switch to turn on the defogger. The defogger
will stay on for about 14 minutes, then will shut off
automatically. You can also turn it off by pressing the
switch again. Use it only when the engine is running.
Make sure you turn the defogger off when the window
is clear. Leaving the defogger on for a long time could
cause the battery to run down, especially during
stop-and-go driving. The defogger is not designed for
drying water or melting snow.
Do not attach anything like a temporary vehicle license
or a decal across the defogger grid on the rear window.
I
NOTICE:
Don't use a razor blade or something else sharp
on the inside of the rear window. If you do, you
could cut or damage the warming grid, and the
repairs wouldn't be covered by your warranty.
Flow-Through Ventilation System
Your Geo's flow-through ventilation system supplies
outside air into the vehicle when it is moving. Outside
air will also enter the vehicle when the heater or the air
conditioning fan is running and the air intake lever is at
CIRCULATE.
Ventilation Tips
Keep the hood and front air inlet free of ice, snow, or
any other obstruction (such as leaves). The heater and
defroster will work far better, reducing the chance of
fogging the inside of your windows.
When you enter a vehicle in cold weather, move the fan
lever toward HI for a few moments before driving off.
This helps clear the intake ducts of snow and moisture,
and reduces the chance of fogging the inside of your
windows.
3-4