Replace the blower motor resistor assembly that controls HVAC fan speeds in a 2011-2014 Ford F-150 with 5.0L V8 engine.

Warnings

Tools required

Parts

• Blower motor resistor assembly × 1 — Motorcraft YH-1779 or equivalent

Preparation

1. Turn ignition to OFF position and remove key
2. Allow HVAC blower motor and resistor to cool if recently operated
3. Position yourself on the passenger side floorboard for access to the resistor location

Procedure

1. 1

   Locate the blower motor resistor
   The blower motor resistor is mounted on the HVAC housing on the passenger side, above the transmission tunnel. It is located behind the glove box area but accessible from underneath the dashboard without removing the glove box. Look for a rectangular component with a wire harness connector and cooling fins.
2. 2

   Disconnect the electrical connector
   Press the locking tab on the resistor wire harness connector and pull straight out to disconnect. The connector may be tight due to corrosion or seal interference. Do not pull on the wires themselves. If stuck, gently work a small flat-blade screwdriver into the connector seam while pulling.
3. 3

   Remove resistor mounting screws
   Using a 7mm socket or nut driver, remove the two screws securing the blower motor resistor to the HVAC housing. These screws are typically Phillips-head with 7mm hex heads. Keep these screws as they will be reused unless damaged.
   Torque spec

   Resistor Screws2 Nm (1.5 lb-ft)
4. 4

   Remove the old resistor assembly
   Carefully pull the resistor assembly straight out from the HVAC housing. There is a rubber seal gasket that may cause resistance. Wiggle gently if needed but avoid bending the resistor. Inspect the resistor connector pins for burn marks or corrosion, which indicates electrical problems.
5. 5

   Inspect HVAC housing and connector
   Examine the mounting area on the HVAC housing for melted plastic, burn marks, or debris. Check the wire harness connector for burnt or corroded terminals. If damage is present, the wire harness may also need replacement to prevent repeat failure. Clean any debris from the mounting surface.
6. 6

   Install new resistor assembly
   Verify the new resistor has the rubber seal gasket properly positioned. Align the resistor with the mounting holes and cooling fins oriented toward the blower motor airflow. Push firmly into place ensuring the seal seats completely against the HVAC housing.
7. 7

   Install and torque mounting screws
   Thread both mounting screws by hand first to ensure proper alignment. Using a low-range torque wrench and 7mm socket, tighten the resistor screws to specification in an alternating pattern to ensure even seal compression.
   Torque spec

   Resistor Screws2 Nm (1.5 lb-ft)
8. 8

   Reconnect electrical connector
   Push the wire harness connector onto the resistor until you hear and feel a positive click. Gently tug on the connector to verify it is locked in place. Ensure no wires are pinched or stressed.

Reassembly

1. Ensure no tools or parts are left in the passenger footwell area
2. Verify the electrical connector is fully seated and locked

Verification

• Turn ignition to ON position without starting engine
• Test all blower motor speed settings (typically 1-4 or 1-7 depending on configuration) to confirm each speed works properly
• Listen for smooth operation at each speed with no unusual noises or burning smells
• Verify airflow increases progressively with each speed setting
• Check that the blower motor turns off completely when switched to OFF position

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