Here's a general outline of the process. Always consult a repair manual specific to your 1999 Ford Expedition for detailed instructions and diagrams. These manuals often show the exact location of components and provide torque specifications.
1. Diagnosis:
* Identify the faulty actuator: Is it the one controlling the temperature (hot/cold) or the mode (vent/defrost/floor)? Determine which blend door isn't functioning correctly. This often involves testing the controls and listening for the actuator motor attempting to run.
* Confirm it's the actuator: A failed blend door itself (the actual door inside the dashboard) is far less common than a failed actuator. Diagnosing this requires more advanced techniques, potentially involving a visual inspection (requiring dashboard removal).
2. Preparation:
* Disconnect the battery: This is crucial for safety to prevent accidental shorts and electrical damage.
* Gather tools: You'll need various tools, including screwdrivers (Phillips and flathead), possibly sockets and ratchets, trim removal tools (plastic pry tools), and potentially a torx bit set. A flashlight is essential.
* Consult a repair manual: This will guide you through the specific steps for your vehicle and help avoid damaging anything.
3. Accessing the Actuator:
* This is the most challenging part. Access varies depending on the specific actuator (temperature or mode). Generally, it involves removing parts of the dashboard. This often means removing the glove box, possibly some trim pieces around the radio and center console, and possibly even parts of the dashboard itself. Be extremely careful not to break any plastic clips during disassembly.
4. Actuator Replacement (or Repair):
* Once you have access, disconnect the electrical connector from the actuator.
* Remove the actuator: This might involve removing screws or other fasteners.
* Inspect the actuator: If it's just the motor that's failed, replacement is the easiest solution. Some try to repair the motor, but this is usually not practical due to the tiny size of the components.
* Install the new actuator: Carefully install the new actuator, ensuring it's properly seated and connected. Reconnect the electrical connector.
5. Reassembly:
* Carefully reassemble all the dashboard components you removed, ensuring everything is securely fastened.
* Reconnect the battery.
* Test the system: Turn on the HVAC system and check that the blend door is functioning correctly.
Important Considerations:
* Cost: Replacing the actuator can be relatively inexpensive, but labor costs can significantly increase the total cost if you have a mechanic do the job.
* Difficulty: This repair can be quite challenging due to limited access and the need for careful disassembly and reassembly of the dashboard.
* Alternatives: If you're not mechanically inclined, consider seeking professional help from a qualified mechanic or automotive repair shop.
This is a general overview. Always refer to a repair manual specific to your 1999 Ford Expedition for detailed instructions and diagrams. Improper repair can lead to further damage. Take your time, be patient, and if you're unsure about any step, don't hesitate to seek professional help.
