Were is the air ride compressor module in 99 Lincoln Navigator?

The air ride compressor module on a 1999 Lincoln Navigator is located underneath the vehicle, typically near the rear suspension. It's often mounted on the frame rail, somewhere in the vicinity of the spare tire or the rear differential. You'll likely see air lines connected to it.

Because the exact location can vary slightly depending on specific model year and trim, you'll need to consult a repair manual specific to your 1999 Lincoln Navigator. A Haynes or Chilton manual will have diagrams showing the location. You can also try searching online for a diagram or a forum post showing the location for a 99 Navigator. Be sure to use the exact year and model when searching.