Ford Mercury Villager 1997 Owner's Manual page 79

Controls and Features
Liftgate Window Features
Rear Window Defogger (If equipped)
The defogger for the rear liftgate window clears frost, fog, or thin
ice from both the inside and outside of the rear window. The
defogger operates with the ignition in the ON position.
If your vehicle is equipped with heated rearview mirrors, they
activate when the rear window defogger is switched on.
The control switch is located on the instrument panel to the right
of the steering column.
Rear window defogger switch location
Before using the defogger, clear away any snow that is on the rear
window and outside rearview mirrors. With the engine
running, push the defroster button.
After approximately 10 minutes, the defroster will turn off. If the
window or mirrors are still not clear, turn the defroster on
again.
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