Blower Motor Definition and Function

What is a blower motor on your car? Many people know about their car’s AC or climate control system, but not the blower motor. If you’re one of them, this first part of the guide will help you understand the component in detail.

Among the topics in the chapter are; blower motor definition, blower motor location, parts, and working principle. There’s also a section about the blower motor price to help you budget for a replacement part. Let’s get started.

What is Blower Motor?

The car blower motor is the component that moves air through a vehicle’s HVAC system. It’s usually a motor and blower assembly, with a metal housing all around it. Some people call it car heater blower or car heater fan. Based on its function, it can also be called the car AC fan.

The blower motor forms part of a vehicle’s climate control system. Other components include the heater core, evaporator, and air ducts. Through the action of the blower, car AC systems ensure passenger and driver comfort by regulating cabin air temperature.

In most modern automobiles, the blower motor is electronically controlled and automatic. Older vehicles use manually controlled blower motors. However, the general construction of the fan assembly remains identical for most versions of the device.

Where is the blower motor located?

In most vehicles today, the blower motor is found underneath the dash or behind the glove box. In older car models, it’s located in the engine bay and within easy reach. When it comes to blower motor replacement, these are the easiest to work on.

the blower motor location under the dashboard
the blower motor location under the dashboard

There are also vehicles, such as large vans and SUVs that come fitted with an additional fan in the rear. The rear AC blower motor for car climate control supplements the standard front blower motor and features a similar construction.

Parts of a Blower Motor

As mentioned earlier, the blower motor comprises an electric motor and fan assembly. The motor rotates the fan, helping to draw and push air through a system containing a heater core, evaporator, and ducts. Below is a list of the main blower motor parts including the function of each.

Electric Motor

The most essential part of the blower assembly is a 12V DC motor, which can either be brushed or brushless. If your car is an older model, it probably uses a brushed motor. The AC fan blower motors in newer cars are usually brushless. These are more efficient, low maintenance, and allow for infinite speed levels.

Motor Blower Housing

The car air blower housing is the cover around the motor, sometimes even the entire blower assembly. It protects the motor and forms the surface by which you mount the device. The housing is normally made from metal for strength and rarely gets damaged. To prevent corrosion, it’s usually coated or painted.

Blower Wheel

This is the fan that rotates to draw air and push it through the HVAC system. It’s usually a round wheel made of plastic and ribbed to create the blower blades. The blower wheel assembly must be clean and free from debris for the blower motor to function properly. If jammed by debris, the result can be a burnt out motor or broken blades.

the blower motor function is to ensure airflow at the car AC vents
the blower motor function is to ensure airflow at the car AC vents

What does a Blower Motor do?

The blower motor function is to rotate the fan that blows cold or hot air into the cabin. Its operation is governed by different components, as we will see in a moment. Being an electric component, the car fan blower working also involves a wiring system and source of electric power. Here is how it works.

  • When you turn on the climate control or AC in your car, the blower motor circuit sends a signal, normally through a relay and control module, that causes the motor to receive power from the car battery

  • The motor gets energized and starts to spin. Its shaft runs through a round wheel known as the blower motor fan or cage. As it spins, it draws air and forces it into the air conditioning and heating system.

  • Depending on the required climate control action, the fan channels air either toward a heater core or evaporator. When the air passes through the heater, its temperature rises. If it passes through the evaporator, its temperature drops and cool air comes out of the AC vents and into the cabin.

  • Most vehicles today come with automatic climate control systems where the speed of the fan is controlled electronically via a module. Older models are fitted with manual controls where temperature is achieved by routing current through different resistors. These allow up to 4 or 5 speeds, compared to the electronic type where speed can be altered gradually.

The blower motor offers many benefits in your car. It ensures a steady stream of hot air in cold weather and cold air in the hot conditions. That way, the cabin remains comfortable to sit in. Without a working car AC blower motor, conditions in the cabin would be unbearable, and driving difficult. Apart from heating and conditioning air, the blower motor in some vehicles is also tasked with running the window defroster system.

The blower motor for car AC systems depends on several other components to work. These include the following.

  • Control module- the operation of modern blower motors is usually controlled by an electronic control module. The module contains a clever circuitry to vary the speed of the blower, most of the time using the input of sensors to determine the right speed. The module allows for automatic cabin climate control.

  • Resistor- what is a blower motor resistor and why is it important? A blower motor resistor controls the amount of current going to the motor and, therefore, the motors speed. By using different resistors, different speed levels are achieved. In modern cars, the blower motor speed control is gradual and based on an ECU.

  • Fuse- a blower motor circuit is normally fitted with a fuse to prevent excessive currents from damaging the parts of the HVAC system. The fuse blows when there’s a short circuit or current overload and is one of the reasons for non-functioning AC systems.

  • Relay- some blower motor circuits are equipped with relays. The relays switch on circuits that connect the blower motor to the car battery. This helps to protect the delicate control parts located on the dash.

  • Connectors– these are the cables and wire harnesses the convey signals and electric current to the motor. They ensure power reaches the motor and are essential to its working.

Blower Motor Cost

How much does a car blower motor cost for a car? Knowing the amount that the device goes for will help you make important replacement decisions. So let’s go straight to the figures. The car blower motor price depends on your type of car and model or brand. The cost varies between $50 and $200 mostly. Costly models of the blower motor can carry a price tag of up to $700 or more.

Every car blower motor for sale will have its unique specifications. These define the characteristics of the device and how it fits particular applications. Car blower monitor specifications include values for voltage rating, current draw, toque, CFM, and more. When shopping for one, ensure the specs match what your particular car needs.

Ensure, too, that the replacement motor is identical to the old one. That’s, unless you’re considering upgrading, in which case you would need to consult your mechanic. Blower motor, although generally similar, come in different configurations. You do not want to run into compatibility issues.

Conclusion

As we have seen, the blower motor assembly in your car is an important part when it comes to cabin comfort. By helping to move air through the HVAC ducts, the motor ensures the right temperature levels in the cabin. But that does not always happen. The device, being mechanical and electrical, is prone to all sorts of faults. In the next part of the guide, you will find out what these faults are and how to deal with them.

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