What Is a Car Blower Motor? Purpose, Symptoms, and More

Aside from having plush seats and a clean cabin, great ventilation is another factor that contributes to the overall comfortability of your ride.

Your vehicle’s heating, ventilation, and air conditioning (HVAC) system plays an important role in maintaining proper ventilation in your cabin, especially its blower motor. This part works with the fan switch and lets you adjust the fan settings of your air conditioning (A/C) system according to your preference. But like any other car part, it can wear out or get damaged over time.

Here’s a quick guide about the blower motor and the most common symptoms that could indicate the need to replace it.

What Is a Blower Motor?

The blower motor is a critical part of your vehicle’s HVAC system. It is usually a permanent magnet, one-speed motor that operates at full battery voltage. The path that the current follows to the blower motor is typically controlled by the fan switch via a resistor pack (also known as a blower motor resistor) to achieve different fan speeds.

What Does a Blower Motor Do?

The blower motor turns the blower fan, which forces air through the HVAC system and out of the car’s vents. When the HVAC system is set to heat, the air from the blower motor is directed across the heater core and into the cabin to warm things up. On the other hand, when the A/C is turned on and the temperature is set to cool, the air from the blower motor is directed across the A/C evaporator to cool things down.

Traditionally, the speed of the blower motor was controlled via a switch and resistor assembly. On newer vehicles, however, the blower motor is often controlled via a module, which receives input from the switch on the HVAC control unit.

Blower Motor Speeds

The blower motor relies on the blower motor resistor or control module to obtain different fan speeds. When a traditional resistor is used, the speed is controlled by using a few different electrical paths. The path can be a full-battery voltage for a high-speed operation or a path through one or more resistors to reduce the motor’s voltage and current for a low-speed operation. A blower motor usually works under four speeds.

Low Speed

The current flows through three resistors, dropping the voltage to about four volts and four amperes.

Medium Speed

The current flows through two resistors to lower the voltage to six volts and six amperes.

Medium-High Speed

The current flows through one resistor and lowers the voltage to nine volts and nine amperes.

High Speed

This utilizes full battery voltage through a relay, which is then applied to the blower motor. This generates a current of about 12 amperes.

How Do You Know If Your Heater Blower Motor Is Bad?

A faulty blower motor can result in an uncomfortable car ride, which is why it’s important to pay attention to any sign of trouble. Here are the most common symptoms that point to a bad blower motor.

Weak Airflow or No Airflow at All

Weak airflow or no airflow from the vents is a common sign of a worn-out blower motor. Blower motors are subject to wear and tear like any other car part, which could hamper the flow of air coming from the HVAC system. Aside from weak airflow, a worn-out blower motor could also affect the defroster’s efficiency.

However, keep in mind that various issues, such as clogged or damp air filters, mold build-up, or a corroded A/C compressor, can also cause weak airflow. To be sure, it’s best to take your vehicle to an auto repair shop and have a certified mechanic inspect your HVAC system.

Abnormal Whirring or Rattling Noises

An issue with the blower motor assembly, such as wear to the bearing or other internal components, can result in an abnormal whirring or rattling noise everytime you turn on the HVAC fan.

How Much Does It Cost to Replace a Blower Motor?

A new blower motor will generally cost anywhere between $50 and $200, depending on factors like its brand and your vehicle’s year, make, and model. Labor costs for a blower motor replacement typically range from $100 to $500, depending on your vehicle’s specifications.

What Causes a Blower Motor to Go Bad?

A defective ground wire or ground wire connection and an open circuit in the power-side circuit (including the fuse, wiring, and fan switch) are the most common reasons why a blower motor fails. Blower motors can also just fail from regular use due to time and mileage.

Here is a video you can check to see how to test if a blower motor is bad:

How to Get a Quality Car Blower Motor

Driving with a damaged blower motor can make your road trips extremely uncomfortable, which is why it’s a good idea to shop for a replacement right away. The good news is that CarParts.com is always ready to help you find the right part for your ride. 

CarParts.com’s vehicle selector makes it easy to find compatible replacement parts for your daily driver. All you have to do is enter your vehicle’s year, make, and model to choose from a wide selection of direct-fit blower motor replacements. All our products passed stringent quality checks, so you’re sure to get an OE-grade blower motor. 

What’s more, you don’t even have to get up from your seat to buy a new blower motor. After placing your order, it’ll only take a few days before your product is delivered straight to your doorstep, thanks to our website’s fast shipping service.

Enjoy a refreshing and comfortable road trip when you buy a replacement blower motor for your ride from CarParts.com today.