Blower Motor Resistor

This procedure replaces the blower motor resistor, which controls fan speed for the HVAC system, located under the passenger side of the instrument panel.

Warnings

Tools required

Parts

• Blower motor resistor × 1 — ACDelco 15-81638 or equivalent

Preparation

1. Park vehicle on level surface and engage parking brake
2. Turn ignition off and remove key
3. Allow HVAC system to cool completely if recently operated
4. Disconnect negative battery terminal and wait 2 minutes before proceeding

Procedure

1. 1

   Disconnect negative battery terminal
   Using a 10mm wrench or socket, loosen the negative battery terminal bolt. Remove the cable from the battery post and secure it away from the terminal to prevent accidental reconnection during the repair.
   Torque spec

   Battery Terminal Bolts8 Nm (6 lb-ft)
2. 2

   Access passenger side footwell area
   Move the passenger seat fully rearward to maximize working space. Remove any floor mats or obstructions from the passenger footwell area. You will be working under the right side of the instrument panel near the center console.
3. 3

   Locate the blower motor resistor
   Position yourself in the passenger footwell looking upward toward the HVAC housing. The blower motor resistor is mounted on the lower right side of the HVAC module, accessible from below. It has a multi-pin electrical connector attached and is secured by two screws. Use a flashlight to clearly identify the component.
4. 4

   Disconnect electrical connector
   Locate the electrical connector on the blower motor resistor. Press the release tab on the connector while pulling it straight away from the resistor. If the connector is tight, gently wiggle it side to side while pulling. Do not pull on the wires themselves.
5. 5

   Remove resistor mounting screws
   Using a 7mm socket or nut driver, remove the two screws securing the blower motor resistor to the HVAC module housing. These screws may have thread-locking compound and require moderate force to break free. Support the resistor with one hand as you remove the second screw to prevent it from falling.
   Torque spec

   Resistor Screws2 Nm (1.5 lb-ft)
6. 6

   Remove old resistor
   Carefully pull the blower motor resistor straight out from the HVAC module housing. The resistor may have a rubber seal or gasket that creates some resistance. Note the orientation of the resistor and any seal for proper installation of the new component.
7. 7

   Inspect HVAC housing and seal
   Examine the mounting surface on the HVAC housing for debris, moisture, or damage. Clean the surface with a dry cloth if needed. Check the seal or gasket on the old resistor; if the new resistor does not include a new seal, carefully remove the seal from the old unit for reuse, ensuring it is not torn or damaged.
8. 8

   Install new blower motor resistor
   Position the new resistor with seal properly oriented to match the removal position. Align the resistor with the mounting holes and carefully push it into the HVAC module housing until it seats flush against the mounting surface. Ensure the seal is properly positioned to prevent air leaks.
9. 9

   Install resistor mounting screws
   Start both mounting screws by hand to ensure proper thread engagement and alignment. Using a torque wrench with 7mm socket, tighten the screws alternately in a cross pattern to 2.0 Nm (1.5 lb-ft). Do not overtighten as the screws thread into plastic or soft material.
   Torque spec

   Resistor Screws2 Nm (1.5 lb-ft)
10. 10

    Reconnect electrical connector
    Align the electrical connector with the terminals on the new blower motor resistor. Push the connector firmly onto the resistor until you hear or feel a positive click, indicating the locking tab has engaged. Gently tug on the connector to verify it is fully seated and locked.
11. 11

    Reconnect battery
    Reconnect the negative battery cable to the battery terminal. Tighten the terminal bolt to 8.0 Nm (6.0 lb-ft) using a torque wrench.
    Torque spec

    Battery Terminal Bolts8 Nm (6 lb-ft)

Reassembly

1. Ensure all electrical connections are secure and properly locked
2. Verify no tools or parts remain in the passenger footwell area
3. Return passenger seat to desired position and replace floor mats

Verification

• Turn ignition to ON position without starting engine
• Test all blower motor fan speeds (typically 1-5 settings) using the climate control panel
• Verify each speed operates correctly with appropriate airflow increase at each level
• Listen for smooth operation without unusual noises or hesitation between speed changes
• If equipped, test AUTO mode to ensure automatic fan speed control functions properly
• Confirm no warning lights appear on the instrument cluster related to HVAC system

Related trouble codes on this vehicle

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