A fanor cooler relay is used in an electric furnace to change the blower speed the?

A fan or cooler relay is used in an electric furnace to change the blower speed based on the temperature of the furnace. When the furnace is turned on, the relay sends power to the blower motor, which starts to blow air through the furnace. As the furnace heats up, the relay gradually increases the speed of the blower motor, so that more air is blown through the furnace and the heat is distributed more evenly throughout the house. When the furnace reaches the desired temperature, the relay turns off the blower motor, and the furnace stops blowing air.