Blower Motor Resistor

This procedure replaces the blower motor resistor, which controls the HVAC fan speeds in the 2007 Ram 3500. The resistor is located behind the glove box and is accessible without removing the dash.

Warnings

Tools required

Parts

• Blower motor resistor × 1 — Use OEM Mopar part or equivalent

Preparation

1. Turn off the ignition and remove the key
2. Set the HVAC controls to the off position
3. Open the passenger side door for easier access to the glove box area
4. Allow the blower motor resistor to cool if the vehicle was recently running with HVAC on

Procedure

1. 1

   Remove glove box door
   Open the glove box fully. Locate the stops on each side of the glove box that prevent it from opening too far. Squeeze the sides of the glove box inward to release the stops, then lower the glove box door completely to hang down and expose the area behind it.
2. 2

   Locate blower motor resistor
   Look up and to the right side of the HVAC housing behind where the glove box was located. The blower motor resistor is mounted on the side of the HVAC case near the blower motor. It will have a wiring harness connector attached and is secured by two screws. Use a flashlight to identify the component if needed.
3. 3

   Disconnect electrical connector
   Locate the electrical connector on the blower motor resistor. Press the release tab on the connector and pull it straight out from the resistor. The connector may be tight due to years of heat cycling - gently wiggle it while pulling if needed, but do not force it to avoid breaking the connector.
4. 4

   Remove resistor mounting screws
   Using the appropriate socket or nut driver (typically 5.5mm or 8mm on this platform — verify the size on your vehicle), remove the two screws securing the blower motor resistor to the HVAC housing. Keep track of these screws as they are small and can easily fall into the HVAC case or behind the dash.
5. 5

   Remove old resistor
   Pull the blower motor resistor straight out from the HVAC housing. The resistor has a mounting flange that seats into the housing. If it is stuck due to the seal or corrosion, gently wiggle it while pulling to break it free. Inspect the old resistor for signs of burning, melted plastic, or corroded terminals.
6. 6

   Inspect blower motor and housing
   Before installing the new resistor, inspect the opening in the HVAC housing where the resistor mounts. Check for debris, leaves, or signs of water intrusion. Also verify the blower motor connector and visible wiring are in good condition, as a failing blower motor can cause premature resistor failure.
7. 7

   Install new resistor
   Position the new blower motor resistor with the mounting flange aligned to the opening in the HVAC housing. Push it firmly into place until it seats completely flush against the housing. The resistor should sit flat with no gaps.
8. 8

   Install mounting screws
   Insert and tighten the two mounting screws to secure the resistor to the HVAC housing. Tighten by hand until snug - do not overtighten as the housing is plastic and can crack. The screws only need to be tight enough to hold the resistor firmly in place.
9. 9

   Reconnect electrical connector
   Push the electrical connector onto the blower motor resistor until it clicks into place. Ensure the connector is fully seated and the locking tab engages properly. Gently pull on the connector to verify it is secure.
10. 10

    Reinstall glove box
    Lift the glove box door back up into position. Squeeze the sides inward to clear the stops, then release the sides so the stops engage with the dash frame. Close the glove box and verify it operates normally.

Reassembly

1. Ensure the glove box opens and closes smoothly and latches properly
2. Verify all tools and fasteners have been retrieved from the work area

Verification

• Turn the ignition to the ON position without starting the engine
• Set the HVAC fan control to each speed setting (Low, Medium-Low, Medium-High, and High) and verify the blower motor operates at each speed
• Listen for smooth operation with no unusual noises or hesitation between speeds
• Verify airflow increases appropriately with each higher fan speed setting
• If any speed setting does not work, recheck the electrical connector and resistor installation

Related trouble codes on this vehicle

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