The coolant can exceed a certain temperature to open the thermostat when you turn on the defroster in the front car. Hot water flows through the heater centre. While the blower fan moves warm air through the defroster winds and warms the walls. As the window reaches the desired temperature, condensation or ice may start disappearing.
These frost pads will also eliminate fog that accumulates in the car in addition to eliminating the condensation at the outside of the vehicle. This also happens when the outside weather is cooler and warm indoors.
The rear window lines are electrical. When the rear defrost is triggered, they heat up and immediately begin removing the condensation. The electric defrost bonus is that as soon as you turn the vehicle on and set the rear defrost button, it starts working. For it to be effective, the front defrosts with the fan and blower must wait until the vehicle temperature warms up. Many new models have electronic defrost along the front windshield edges to boost the defrost system and eliminate condensation more easily.