Blower Motor Resistor

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

Warnings

Tools required

Parts

• Blower motor resistor × 1 — Use OEM specification

Preparation

1. Park vehicle on level ground and engage parking brake
2. Turn ignition off and remove key
3. Allow HVAC system to cool if recently operated
4. Open passenger door fully for access

Procedure

1. 1

   Disconnect battery negative terminal
   Open the hood and disconnect the negative battery terminal. Loosen the terminal bolt and remove the cable, securing it away from the battery post to prevent accidental reconnection during the repair.
   Torque spec

   Battery Terminal Bolts7 Nm (5 lb-ft)
2. 2

   Access blower motor resistor location
   On these Dodge Ram trucks the blower motor resistor is typically accessed from the engine compartment on the passenger side, mounted on the HVAC/blower housing on the firewall near the blower motor. Verify the exact location for your specific model year, as access may be from the engine bay rather than the interior footwell. You may need to remove the under-dash insulation panel or push aside carpeting for better access. Use a flashlight to locate the resistor connector and mounting screws.
3. 3

   Disconnect electrical connector
   Locate the electrical connector attached to the blower motor resistor. Depress the locking tab on the connector and carefully pull it straight off the resistor terminals. Do not pull on the wires themselves. If the connector is difficult to access, use needle-nose pliers to depress the locking tab.
4. 4

   Remove resistor mounting screws
   Remove the screws securing the blower motor resistor to the HVAC housing (verify the exact screw count and driver size for your model year). A nut driver with a short extension is typically required. These screws may be tight due to corrosion or heat cycling. Keep track of the screws as they are small and easily lost in the footwell area.
   Torque spec

   Resistor Screws2 Nm (1.5 lb-ft)
5. 5

   Remove old resistor
   Carefully pull the blower motor resistor straight out of the HVAC housing. The resistor may be stuck due to the rubber seal or corrosion. Twist gently while pulling if needed. Inspect the old resistor for burn marks, melted connectors, or broken resistance coils to confirm failure.
6. 6

   Inspect housing and connector
   Examine the opening in the HVAC housing for debris, signs of overheating, or damage. Check the electrical connector terminals for corrosion, melting, or burning. If the connector shows heat damage, it should be replaced to prevent premature failure of the new resistor. Clean any debris from the mounting area.
7. 7

   Install new resistor
   Insert the new blower motor resistor into the HVAC housing opening, ensuring proper alignment with the mounting screw holes. The resistor cooling fins should face into the airflow path. Push firmly until the resistor seats completely against the housing.
8. 8

   Install mounting screws
   Install the mounting screws and tighten snugly by hand — these screws thread into plastic housing and do not have a published torque spec. Do not over-tighten, as this will strip the plastic threads. These screws require very light torque as they thread into plastic housing. Over-tightening will strip the threads. If using a torque wrench is impractical in the tight space, tighten screws snug by hand, then approximately 1/8 turn with the socket.
   Torque spec

   Resistor Screws2 Nm (1.5 lb-ft)
9. 9

   Reconnect electrical connector
   Push the electrical connector firmly onto the resistor terminals until the locking tab clicks into place. Tug gently on the connector to verify it is fully seated and locked. Ensure no wires are pinched or stressed.
10. 10

    Reconnect battery
    Return to the engine compartment and reconnect the negative battery terminal. Tighten the terminal bolt securely (typically around 5-8 Nm / 4-6 lb-ft; verify against OEM spec). Ensure the terminal is secure and cannot be moved by hand. Ensure the terminal is secure and cannot be moved by hand.
    Torque spec

    Battery Terminal Bolts7 Nm (5 lb-ft)

Reassembly

1. Reinstall any under-dash panels or insulation that were removed during access
2. Reposition floor carpeting to original position
3. Close passenger door and hood

Verification

• Turn ignition to RUN position without starting engine
• Turn blower motor switch through all speed settings (Low, Medium-Low, Medium-High, High)
• Verify blower motor operates at all speed settings with appropriate airflow changes
• Listen for unusual noises from the blower motor indicating binding or debris
• Check that no blown fuses occurred during testing
• Test HVAC controls in both heat and A/C modes to confirm normal operation

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

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