There is no air ride in the LS,..maybe your thinking Mark VIII or Towncar??
Yes, but it's not safe
Best bet is E-Bay
Passenger side behind the wheel well liner.
Air conditioning compressor? air ride compressor? question not clear enough.
The best bet would be to do a Google search and you'll get an answer.
sensor, go to markviii.org they have a total break down of the air ride
a bad solenoid will prevent the air ride from automatically adjusting the ride comfort,for example,if the car has extra weight in trunk, the air ride will not kick in and level the car,
I believe the compressor is inside the passenger wheel well closer to the front bumper.
Behind the wheel well liner on the passenger side toward the front of the car.
To check the bags, soapy water them and if you see bubbles then you know you have a leak.
Out on the market there is a Ray's Kit that does that, go to Lincoln vs Cadillac .com forum and do a search.