The blower motor resistor in a 2005 GMC Sierra is a crucial component responsible for controlling the speed of the blower motor, which circulates air through the vehicle's heating and air conditioning system. If you're experiencing issues such as weak airflow, the blower motor only working on certain settings, or no airflow at all, it may be time to check or replace the blower motor resistor.

Understanding the Blower Motor Resistor

The blower motor resistor regulates the voltage supplied to the blower motor, allowing for different fan speeds. Common symptoms indicating a faulty resistor include:

  • The blower motor only works on high speed.
  • The blower motor is stuck on one speed.
  • No air is blowing from the vents, even when the system is turned on.

These issues often arise due to wear and tear or electrical problems within the resistor.

How to Replace the Blower Motor Resistor

Replacing the blower motor resistor is a straightforward process that can be done with basic tools. Here’s a step-by-step guide:

1. Gather Tools and Parts: You will need a 7mm socket wrench or a 5.5mm socket, a new blower motor resistor (part numbers like AC Delco 22807123 or Dorman 973-409 are common), and possibly a flathead screwdriver.

2. Locate the Resistor: The blower motor resistor is typically located near the blower motor itself, which can be found under the dashboard on the passenger side of the vehicle.

3. Remove the Cover: Use your socket wrench to remove any screws holding the cover in place. Carefully pull off the cover to access the resistor.

4. Disconnect Wiring: Unplug the wiring harness connected to the resistor. Be cautious not to damage any surrounding components.

5. Remove the Old Resistor: Unscrew the old resistor from its mounting position and remove it from its housing.

6. Install the New Resistor: Position the new resistor in place and secure it with screws. Reconnect the wiring harness ensuring it clicks into place.

7. Reassemble: Replace any covers you removed during this process and ensure everything is securely fastened.

8. Test Functionality: Start your vehicle and test the blower motor at different settings to confirm that it operates correctly across all speeds.

Important Considerations

  • Compatibility: Ensure that you purchase a resistor compatible with your specific model year (1999-2007 models generally share similar components).

  • Electrical Checks: Before replacing, it's wise to check for any electrical issues such as blown fuses or damaged wiring that could affect performance.

  • Safety First: Always disconnect your vehicle's battery before working on electrical components to avoid shocks or short circuits.

FAQs About GMC Sierra Blower Motor Resistor

    • What are common symptoms of a failing blower motor resistor?
      Common symptoms include weak airflow, blower only working on high speed, or no airflow at all.

    • How much does it cost to replace a blower motor resistor?
      The cost for parts typically ranges from $20 to $50, depending on brand and retailer.

    • Can I replace the blower motor resistor myself?
      Yes, replacing it is generally straightforward and can be done with basic tools.

By following these guidelines, you can effectively troubleshoot and replace your GMC Sierra's blower motor resistor, restoring proper airflow and comfort in your vehicle.