How Does a Blower Motor Work?
The motor is usually located within the heater box, which is situated at the front of the passenger compartment, although it is possible to have two separate heater boxes (and thereby blower motors) within larger vehicles, such as an SUV. When cool air is required, the air is “blown” through the evaporator and when warm air is needed, it is pushed through the core of the heater. When activated, power is applied to the motor that will activate the fan causing it to spin, pushing large volumes of air through vents into the passenger compartment.
As temperature conditions within the car can vary so greatly, a variable speed blower motor can be controlled through a several selectors, linked to resistors and relays. When each resistor is selected, the amount of current that flows through the motor is restricted and this will govern the rotation of the blower fan. When “maximum” is selected on the dashboard, this will typically bypass all resistors and connect the fan directly to the prime source instead.