Ford 2006 Expedition Owner's Manual page 661

If a load is added to, or removed from the vehicle, the load leveling
feature of the air suspension system will adjust the suspension to keep
the vehicle at a constant level.
When exiting the vehicle, the air suspension will automatically lower the
vehicle to its lowest height to provide easier exit. You may hear a buzz or
click from the air suspension system when the ignition is turned off. The
air suspension system will stay active for 40 minutes after the ignition is
turned off to accommodate any load changes. (The air compressor may
run when the vehicle is off; this is normal.)
The air suspension shut-off switch is
located behind an access panel on
the left rear quarter trim panel, near
the liftgate. To remove the panel,
turn the control counterclockwise.
On vehicles equipped with
air suspension, turn the air
suspension and the ignition switch
off prior to jacking, hoisting or
towing your vehicle.
Press the bottom portion of the
switch to turn off the air
suspension.
2006 Expedition (exd)
Owners Guide (post-2002-fmt)
USA (fus)
Driving
253