How to Fix Your Car Blower Motor: A Step-by-Step DIY Guide

Is your car’s blower motor failing? If you’re only getting air on the highest setting, or worse, no air at all, you might think you’re facing an expensive repair. While a mechanic might quote you a hefty price for a new blower motor, the truth is, often the issue is simpler than a complete motor failure. Like many car components, the blower motor has parts that wear out over time, specifically the brushes. Instead of shelling out hundreds for a new unit, you can often rebuild your existing blower motor for a fraction of the cost. This guide will walk you through how to diagnose and fix your car’s blower motor, saving you money and keeping your car comfortable.

Before we dive in, it’s worth noting a common, simpler blower motor issue: the fan resistor. If your blower motor only works on the highest speed setting, the problem is likely a faulty fan resistor, not the motor itself. Replacing the resistor is a much easier and cheaper fix. However, if your blower motor is completely dead on all settings, or makes unusual noises, then rebuilding the motor is a smart next step.

Let’s explore how you can bring your blower motor back to life.

Step 1: Removing the Blower Motor from Your Car

The first step is to access and remove your car’s blower motor. The location of the blower motor varies depending on your vehicle’s make and model, but it’s commonly found under the dashboard on the passenger side. Refer to your car’s repair manual or search online for videos specific to your car model that demonstrate blower motor removal. Generally, this process involves:

• Locating the blower motor housing (usually a plastic enclosure).
• Disconnecting the electrical connector to the blower motor.
• Removing any screws or bolts securing the blower motor assembly.
• Carefully extracting the blower motor from its housing.

This process is usually straightforward and requires basic hand tools. Take your time and be gentle with plastic parts to avoid breakage.

Step 2: Inspecting the Blower Motor and Optional Bearing Flush

Once the blower motor is removed, give it a thorough visual inspection.

• Fan Damage: Check the blower fan (squirrel cage) for any cracks, chips, or signs of damage. A damaged fan can cause imbalance and noise, even if the motor is functioning.

Alt text: Close-up of a car blower motor fan showing undamaged blades, highlighting the importance of checking for physical damage during inspection.

• Bearing Condition (Optional Flush): Blower motors use bearings that can become contaminated with carbon dust from worn brushes, leading to premature failure. While optional, flushing out the bearings can extend the life of your rebuilt motor. To do this:
  • Carefully remove the blower fans from both ends of the motor shaft. These are usually press-fit and can be removed by gently twisting and pulling. Be patient as the plastic can be brittle.
  • Marking the Fans: Before removing the fans, mark the position of one fin on each fan relative to the shaft. This helps maintain balance when reinstalling them.
  • Once a fan is off, use a vice grip to hold the shaft steady while you remove the other fan.
  • Using WD-40 (or a similar penetrating lubricant) with the red straw, spray directly into the bearings at each end of the motor. Try to flush out any dirt and debris.
  • Caution: Avoid getting WD-40 on the commutator (the copper part of the motor shaft where the brushes make contact). If you do, clean it thoroughly with electronic contact cleaner in the next step.

Alt text: Detail shot of WD-40 being applied to the bearing of a disassembled car blower motor, illustrating the bearing flush procedure for maintenance.

Step 3: Examining the Brushes

The brushes are the most common wear item in a blower motor. They are small carbon blocks that conduct electricity to the rotating part of the motor. Over time, these brushes wear down due to friction.

Locate the brush housings on the blower motor. These are usually rectangular slots on the motor casing. Inspect the brushes:

• Wear Level: Note how much of the brush is remaining. If they are significantly worn down (less than ¼ inch remaining), replacement is necessary. In the example below, the brushes are about half worn, indicating they would soon need replacement.

Alt text: Image of blower motor brushes housed in rectangular slots, illustrating the location and typical wear points of brushes requiring inspection.

Step 4: Sourcing Replacement Carbon Brushes and Contact Cleaner

Now that you’ve identified worn brushes, you’ll need to get replacements. Head to your local auto parts store or a hardware store like Ace Hardware.

• Carbon Brushes: Purchase a set of carbon brushes that are close in size to the originals. The brushes in the original article were approximately 5mm x 8mm x 15mm, but it’s best to measure your old brushes if possible or bring one with you for comparison. You may need to slightly modify them, but often, you can find a direct fit.

Alt text: Display of new carbon brushes purchased for car blower motor repair, emphasizing the availability of replacement parts for DIY fixes.

• Electronic Contact Cleaner: Also, purchase a can of electronic contact cleaner. This is essential for cleaning carbon dust and ensuring good electrical connections.

Alt text: Can of electronic contact cleaner, highlighting its use in cleaning electrical components during car blower motor maintenance and repair.

• Comparison: Compare the new brushes to the old ones. You can see the difference in wear. Even brushes that are not completely worn can be the cause of intermittent blower motor problems.

Alt text: Side-by-side comparison of new and worn carbon brushes from a car blower motor, clearly showing the material loss due to wear and tear.

Step 5: Removing the Old Brushes

Carefully remove the old brushes from their housings:

• Access Tabs: Use needle-nose pliers to gently bend open the small metal tabs that retain the brushes in their slots.
• Caution: Springs: Be extremely careful, as there is a small spring behind each brush that will push it out. Don’t lose these springs; you’ll need to reuse them. Only bend the tabs open once or twice, as they can break if bent repeatedly.
• Wire Leads: Examine how the brush wires are connected. Typically, one wire is soldered to a terminal, and the other is crimped.
• Cutting Crimped Wire: For the crimped wire, do not try to pull it out of the crimp. The plastic brush holder can be brittle. Instead, use wire cutters to cut the wire, leaving about ½ inch (1 cm) of wire protruding from the crimp.
• Desoldering Soldered Wire: Desolder the wire from the other terminal.

Alt text: Hands using needle-nose pliers to carefully remove worn carbon brushes from their housing in a car blower motor, detailing the disassembly process.

Alt text: Detailed view of the wire connections to car blower motor brushes, showing both crimped and soldered types, essential for understanding replacement procedures.

Step 6: Installing the New Brushes

Installing the new brushes requires some dexterity:

• Spring Placement: Ensure the wire lead of the new brush passes through the bottom of the spring before you insert the brush into the housing. This prevents the spring from pulling on the wire as the brush wears down in the future.
• Orientation: Aftermarket brushes might be rectangular instead of square like the originals. Make sure to orient the brush so its longer side is parallel to the commutator’s rotation (the shorter sides facing the tabs). This ensures proper contact.
• Securing Brushes: Use a small flat-head screwdriver to hold the spring compressed while you use pliers to bend the tabs back down, securing the new brush in place. Again, be careful not to let the spring pop out.

Alt text: Hands installing new carbon brushes into the blower motor housing, demonstrating the spring compression and tab securing technique for brush replacement.

Step 7: Resoldering Brush Wires

Reconnect the brush wires:

• Prepare Wire Ends: Tin the ends of both the new brush wire and the remaining wire from the old crimped connection. Also, tin the solder pad where the other brush wire was originally connected.
• Soldering: For the crimped side, lay the tinned wire from the new brush alongside the remaining centimeter of wire from the old brush and solder them together. Avoid simply twisting the wires. A good solder joint ensures a reliable electrical connection.
• Solder Pad Connection: Solder the other brush wire to its solder pad.
• Reinforce Wire (Pro-tip): Tin a small length of the wire beyond the solder joint to add rigidity. This prevents the wire from flexing too much and potentially shorting out.

Alt text: Close-up of the resoldering process for new blower motor brushes, highlighting the technique for creating a secure and electrically sound connection.

Step 8: Cleaning and Reassembly

Final steps before reinstalling:

• Clean with Contact Cleaner: Thoroughly spray the brushes, commutator, and surrounding area with electronic contact cleaner. This removes carbon dust and ensures clean operation.
• Reinstall Fans: Reinstall the blower fans onto the motor shaft, aligning them according to the marks you made earlier to maintain balance. The fan on the brush side might not go all the way down the shaft – position it so that the shiny part of the shaft is no longer visible.

Step 9: Reinstalling the Blower Motor

The final step is to reinstall the rebuilt blower motor back into your car. Reverse the removal process from Step 1:

• Carefully place the blower motor back into its housing.
• Secure it with the screws or bolts you removed.
• Reconnect the electrical connector.

Alt text: Image of a rebuilt car blower motor reinstalled and ready for use, symbolizing successful DIY repair and cost savings.

Test and Enjoy the Airflow!

Turn on your car and test the blower motor at all speed settings. Initially, you might hear some noise as the new brushes wear in and conform to the commutator. This is normal and should disappear after a short period of use.

By rebuilding your blower motor, you’ve saved yourself a significant amount of money and gained valuable DIY auto repair experience. You’ve also extended the life of your car and contributed to reducing unnecessary waste. Enjoy the comfortable airflow in your car once again!