Is your car’s air conditioning or heating fan only working on the highest setting? This is a common symptom of a failing blower motor resistor. Instead of rushing to replace the entire blower motor, you might just need to repair the resistor. This guide will walk you through the process of repairing your car’s blower resistor, potentially saving you time and money. This DIY repair is applicable to many vehicles and we will be focusing on a common issue found in models like the Honda Fit.
Symptoms of a Faulty Blower Resistor
Before you start taking things apart, it’s important to confirm that the blower resistor is indeed the problem. Here are the typical signs of a failing blower resistor:
- Fan only works on high speed: This is the most classic symptom. Lower fan speeds are controlled by the resistor, while the highest speed often bypasses it. If only high speed works, the resistor is a prime suspect.
- No fan operation at all: In some cases, a completely failed resistor can result in no fan operation on any speed.
- Intermittent fan operation: Sometimes, the fan might work intermittently, cutting in and out on lower speeds before failing completely.
If you’re experiencing these issues, especially the first one, repairing the blower resistor is a worthwhile DIY project to attempt.
Tools and Materials You’ll Need
For this repair, you’ll need a few basic tools:
- Screwdrivers (usually Phillips head)
- Soldering iron and solder
- Possibly a small socket set or wrench (depending on your car model)
Step-by-Step Blower Resistor Repair Guide
Let’s get started with the repair process. While the exact location and removal process might vary slightly depending on your car’s make and model, the general principles remain the same. For this guide, we’ll reference the Honda Fit as an example, as highlighted in the original repair case.
Step 1: Accessing the Blower Resistor
The blower resistor is typically located in the HVAC system housing, often under the passenger side dashboard.
- Remove the passenger-side dashboard undercover. This is usually held in place by clips and pins. Gently pull down the front edge to detach the clips and then pull the cover towards you to release the pins.
Step 2: Removing the Blower Resistor
Once the undercover is removed, you should be able to locate the blower resistor. It usually has a connector and is held in place by screws.
- Disconnect the connector attached to the blower resistor.
- Remove the two screws securing the blower resistor to the HVAC housing.
- Carefully remove the blower resistor from its location.
Step 3: Disassembling and Repairing the Resistor
Now that you have the blower resistor out, you need to disassemble it to access the faulty solder joint.
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Remove/slide off the black plastic base from the resistor assembly.
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Pinch together the metal tips holding the square metal screen housing and slide the housing off the resistor. You may need to gently bend these tips to release the housing.
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Identify the broken solder joint. The most common issue is a poor solder joint on one of the copper filaments. Look for a cracked or detached solder point, often indicated by a visible gap.
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Resolder the copper filament. Using your soldering iron, carefully reheat the solder joint and apply fresh solder to create a strong and reliable connection. You may need to hold the copper filament in place while soldering as it might be under slight tension.
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Reassemble the blower resistor in the reverse order of disassembly. Remember to bend the metal tips back to secure the square metal screen housing.
Step 4: Reinstalling the Blower Resistor
With the resistor repaired and reassembled, it’s time to put it back in your car.
- Install the blower resistor back into the HVAC housing and secure it with the two screws.
- Reconnect the connector to the blower resistor.
Step 5: Testing the Repair
Before putting everything back together, test your repair!
- Turn on your car’s ignition and test the HVAC fan at all speed settings. If the repair was successful, the fan should now work on all speeds.
Step 6: Reinstalling the Dashboard Undercover
If the fan is working correctly, finish the job by reinstalling the passenger’s dashboard undercover.
- Reinstall the passenger’s dashboard undercover by pushing the pins and clips securely into place. Replace any damaged clips if necessary.
Conclusion
Congratulations! You’ve successfully repaired your car’s blower resistor. This simple solder repair can often fix the common issue of the fan only working on high, saving you the cost of a new resistor or even a blower motor assembly. By tackling this DIY repair, you’ve gained valuable experience and kept your car’s HVAC system running smoothly. Remember that while this guide is based on a Honda Fit, the general principles of blower resistor repair are applicable to many vehicles. If you are unsure about any step, always consult a professional mechanic.
