Necessary preliminary work:
Pull storage compartment (1) in the upper area out and fold down as shown.
Release screws (2) on fresh air grille (1).
Lift the fresh air grille (2) upper over the locking tabs (1) and remove toward the front.
Disconnect associated plug connection (3).
Remove fresh air grille (2).
BMW X3 Service & Repair Manual > Alternator with drive and mounting: Removing and installing or replacing alternator (N55)
Necessary preliminary tasks:
Switch off ignition
Disconnect BATTERY EARTH LEAD and cover.
REMOVE LEFT CHARGE AIR DUCT .
Remove alternator DRIVE BELT .
NOTE: In order to remove the alternator, it is necessary to remove .
In so doing:
Do not draw off air conditioning refrigerant.
...