At the heart of most automotive HVAC systems is a component called a blower motor. This descriptive term refers to the fact that these components are electric motors that are attached to fans and used to move air through the HVAC system. In most cases, a single blower motor is responsible for delivering both hot and cool air, on demand, depending on how the climate controls are set.
A blower motor can typically be found in the heater box, although every vehicle is configured a little differently. Some blower motors are easy to access, and others are buried under the dash. Most passenger cars and trucks have heater boxes and blower motors that are located inside the passenger compartment, but there are some instances where the heater box, blower motor, or both, are located in, and accessed from, the engine compartment.
The operation of a blower motor is relatively simple. When voltage is applied to the electric motor, it spins. In turn, that causes the fan to spin. Since the motor assembly is bolted in place, typically inside a heater box, the fan is able to move relatively large volumes of air at high velocities.