How does a blower work on a car?

A car’s blower motor, also known as a heater blower motor or HVAC blower motor, is an electric motor that powers a fan to circulate air through the vehicle’s heating, ventilation, and air conditioning (HVAC) system. It draws power from the car’s battery and is controlled by relays, switches, and resistors or a more modern control module. The blower motor’s fan forces air through the system, either across the heater core for heating or the evaporator for cooling, delivering air to the vents inside the car.

Here’s a more detailed breakdown:

Function:

Circulates air:
The blower motor’s primary function is to move air throughout the HVAC system.
Controls temperature:
It directs airflow over the heater core (for heat) or evaporator (for cooling) to regulate cabin temperature.
Provides airflow:
The fan’s speed determines the volume of air delivered to the vents.
Defrosts and defogs:
It also plays a role in defrosting and defogging the windshield by directing airflow to the vents.

How it works:

Power supply: The blower motor receives electrical power from the car’s battery.
Fan activation: When the driver selects a fan speed, the signal travels through a resistor (older systems) or a control module (newer systems).
Speed control: The resistor or control module regulates the amount of electrical current flowing to the blower motor, thus controlling its speed.
Air circulation: The rotating fan forces air through the system’s ductwork.
Temperature control: The air is directed over the heater core or evaporator, depending on whether heating or cooling is desired, before being distributed through the vents.

Common issues:

Reduced or no airflow: Can be caused by a faulty blower motor, a blown fuse, or a problem with the resistor or control module.
Inconsistent fan speeds: May indicate a problem with the resistor or control module.
Unusual noises: Squealing, rattling, or other noises can be signs of a failing blower motor or debris interfering with the fan.