Hi,
If it happens when you are selecting airflow direction, it is likely related to the mode door actuator. That is what changes the airflow direction. Change airflow direction to see if the sound changes. If it doesn't, try changing from A/C to heat to see if that changes it. That would indicate an issue with a blend air door actuator.
If it is the mode door, here are directions or replacement. The attached pic below correlates with the directions.
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2015 Ford Truck Expedition 2WD V6-3.5L Turbo
Mode Door Actuator - Defrost/Panel/Floor Door
Vehicle Heating and Air Conditioning Air Door Actuator / Motor Service and Repair Removal and Replacement Mode Door Actuator - Defrost/Panel/Floor Door
MODE DOOR ACTUATOR - DEFROST/PANEL/FLOOR DOOR
412-01 Climate Control 2015 Expedition, Navigator
REMOVAL AND INSTALLATION
Mode Door Actuator †Defrost/Panel/Floor Door
Removal
NOTE: The defrost/panel/floor mode door actuator can be accessed from underneath the Left Hand (LH) side of the instrument panel.
Remove the defrost/panel/floor door mode door actuator.
Disconnect the defrost/panel/floor door mode door actuator electrical connector.
Remove the screws and the defrost/panel/floor door mode door actuator.
See Pic 1
Installation
NOTICE: The ignition key must be off when replacing the actuator. Energizing the actuator before installation will cause the part to become positioned incorrectly and proper orientation will be lost. Incorrect actuator operation will result.
To install, reverse the removal procedure.
NOTE: The purpose of the module actuator position calibration is to allow the Heating Ventilation Air Conditioning (HVAC) module to reinitialize and calibrate the actuator stop points. To carry out calibration, carry out the following steps.
Remove Body Control Module (BCM) fuse 46 (10A) for at least one minute.
NOTE: When the ignition switch is switched to the ON position, the HVAC module will initialize and calibrate the actuators. Calibration of the actuators will take approximately 30 seconds.
Reinstall BCM fuse 46 (10A). Turn the ignition switch to the "on" position and wait 30 seconds before verifying the correct mode door actuator operation.
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I hope this helps. Let me know if you have other questions.
Take care and God Bless,
Joe
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Friday, February 26th, 2021 AT 7:11 PM