Chevrolet 1995 Blazer Owner's Manual page 137

Rear Window Defogger (Option)
If your vehicle has this option, the rear window will have lines running
across the glass. These lines heat your window.
For best results, clear the window of as much snow or ice as possible before
using the rear window defogger.
REAR DEFOG
-
To turn on the rear
window defogger, find
the switch marked
REAR DEFOG on
your instrument panel
below the headlight
switch. Press ON until
the light in the switch
comes on, then release
it.
The rear window defogger will stay on for 5 - 7 minutes, then turn off.
It
will only work if the ignition switch is turned to RUN.
You can
turn
the defogger off at any time by pressing OFF. The defogger
will shut itself off after several minutes
so
that the glass does not get too
hot. If the window still isn't clear, turn the defogger on again.
NOTICE:
Scraping the inside of your rear window could cut and damage
the defogger. Your warranty would not cover this damage. Don't
put decals there, either. You might have to scrape them off.
3-3