My 2000 SSEi'* rear compressor isn't working. Does anyone know where it'* located in the car? I assume it'* the compressor and not a leveling switch as the compressor won't come on even when the button is pushed to run it. Any vendors to get one reasonable or even to rebuild it?

Thanks everyone.

I believe it is under the passenger side rear. I know the leveling switch is on the driver'* side though. I would check the wiring to it, and the fuse for the system if it is not making any sounds. I would unplug the connection and look for corrosion, clean the contacts, and put some dielectric grease on them. Had that issue where the contacts in the connector corroded on a ford fuel pump. Found out after when I got it out and both the old and new fuel pumps worked when tested.

make sure you check ELC fuse 30A and ELC relay both in rear fuse block

Thanks...checked the fuses and relay today, although I'm not sure how you test a relay. I'll check the connections as well.

Yep...you are correct! Looks like an old tin bread box.....can't think of any other way to explain it.

Make sure your ride leveling sensor is plugged in. I had a problem with the exhaust valve on my compressor and my bonneville was raked like a musclecar.. I unplugged the sensor and drained the air from the shocks. The best thing is, it looks fine, there is no message on the DLC and the ride really hasnt changed. So my point is behind the left rear wheel toward the front of the car there is a sensor with a little wiper on it. Make sure its plugged in.

to test the relay you should be able to hear it click when battery voltage is supplied to it.
If you remove sensor there should be a breif schematic describing poles. Locate the poles that show a closed circuit . Just hold a wire to one of those polesand to battery terminal then touch other pole to other terminal it should click (thus closing circuit between other two poles).
If it is a 5 pole rrelay then supplying voltage will open normaly closed circuit and close normally open circuit.
If you still have question about relay functionality you can also use multimeter to chec for closed circuit between said poles.

OK...turns out the shocks were bad and needed replaced. Did that, the rear end was waaaaay up..the leveling switch was bad, also. The dealer installed a new one for $250.00 (list price) I found a GM parts dealer I could've bought it from for $150. Lesson learned. Thanks for all the posts.

Wish you had posted that you needed a leveling switch. Some of us have spares laying around.