Defogger

A defogger, demister, or defroster is a system to clear condensation and thaw frost from the windshield, backglass, or side windows of a motor vehicle.

Also, at very low ambient temperatures, the air conditioning system might not turn on, in order to prevent possible compressor damage.

In modern vehicles, running this type of defogger often automatically switches the air conditioning system on, without further action required.

Secondary defoggers, such as those used on a vehicle's backglass and/or side view mirrors, often consist of a series of parallel linear resistive conductors in or on the glass.

Resistive-heat defoggers are usually equipped with an automatic timer to operate for a set time period of 10 to 15 minutes before switching off.