A car heater
and ventilation are closely connected.
The suction suction fan
ensures air is blown into the interior of the car. The heating however is driven by the heater motor which is generally located behind the glove compartment.
works like a radiator as it heats the environment with warm coolant. The cabin suction fan
blows the heat generated by the coolant into the cabin area.
Before being blown into the inside of the car though, the air is rinsed by the cabin air or pollen filter