To be absolutely certain, you should:
* Consult your owner's manual: This is the best source for the specific location on your vehicle.
* Use a repair manual: A Haynes or Chilton manual (or online equivalent) will have diagrams showing the compressor's location.
* Search online: Use a search engine like Google, and include "2007 Buick Lucerne air ride compressor location" to see if someone has already documented its location with photos or videos.
Remember to be careful when inspecting the engine compartment. The engine and other components may be hot, even after the car has been turned off for a while.