Replace the blower motor resistor which controls the HVAC fan speed settings in a 2012-2018 Jeep Wrangler JK.

Warnings

Tools required

Parts

• Blower motor resistor × 1 — Mopar 68078446AB or equivalent

Preparation

1. Park vehicle on level ground and set parking brake
2. Turn ignition OFF and remove key
3. Disconnect negative battery cable and secure away from battery post
4. Allow HVAC system to cool if recently operated
5. Position yourself in the passenger footwell with adequate lighting

Procedure

1. 1

   Locate blower motor resistor
   From the passenger footwell, look up at the HVAC housing near the firewall. The blower motor resistor is mounted on the lower right side of the HVAC housing with an electrical connector and cooling fins visible. It is positioned vertically with the connector facing downward.
2. 2

   Disconnect electrical connector
   Press the red or orange locking tab on the electrical connector and pull straight down to disconnect it from the resistor. The connector may be stiff; wiggle gently while pulling if needed. Note the orientation for reinstallation.
3. 3

   Remove resistor mounting screws
   Using a 7mm socket or nut driver with short extension, remove the two screws securing the resistor to the HVAC housing. These screws thread into plastic and may be tight. Turn counterclockwise carefully to avoid stripping.
   ⚠Do not overtighten screws during reinstallation as the HVAC housing is plastic and threads can strip easily.
4. 4

   Remove blower motor resistor
   Carefully pull the resistor straight out from the HVAC housing. It may require slight twisting or wiggling to break the seal. The resistor has a rubber gasket that seals it to the housing; note its position.
5. 5

   Inspect HVAC housing opening
   Check the mounting surface on the HVAC housing for debris, leaves, or moisture. Clean with a dry cloth if needed. Inspect for any signs of overheating or melted plastic which may indicate additional electrical issues requiring diagnosis.
6. 6

   Prepare new resistor
   Verify the new resistor matches the old unit in connector type and mounting configuration. Ensure the rubber seal/gasket is properly seated on the new resistor. If the gasket is separate, position it correctly on the resistor body.
7. 7

   Install new resistor
   Align the new resistor with the mounting holes in the HVAC housing, ensuring the rubber gasket seats properly. Push firmly until the resistor is flush against the housing. The electrical connector terminals should face downward.
8. 8

   Install mounting screws
   Thread both mounting screws by hand first to ensure proper alignment. Using the 7mm socket and torque wrench, tighten the screws evenly in a cross pattern to the specified torque. Do not exceed torque specification to prevent thread damage in plastic housing.
   ⚠Tighten screws gradually and evenly. Overtightening will strip the plastic threads in the HVAC housing.
   Torque spec

   Cover Screws12 Nm (9 lb-ft)
9. 9

   Reconnect electrical connector
   Align the electrical connector with the resistor terminals and push straight up until the locking tab clicks into place. Tug gently on the connector to verify it is fully seated and locked.
10. 10

    Reconnect battery
    Reconnect the negative battery cable to the battery post. Clean any corrosion from the terminal and cable clamp before connecting. Tighten the terminal bolt to specification using a torque wrench.
    Torque spec

    Battery Terminal Bolts8 Nm (6 lb-ft)

Reassembly

1. Ensure all electrical connectors are fully seated and locked
2. Verify no tools or parts are left in the passenger footwell area
3. Check that battery terminal is tight and secure

Verification

• Start the engine and turn on the HVAC blower motor
• Test all blower speed settings (1, 2, 3, and 4) to verify each speed operates correctly
• Listen for smooth operation without unusual noises or hesitation between speeds
• Verify airflow strength increases progressively with each speed setting
• Check that the blower motor shuts off completely when turned to the OFF position
• Monitor for any burning smell which would indicate improper installation or continuing electrical issues

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