1999 Cadillac Deville Rear Suspension

Is the compressor continuing to run at all times? Most often there is a fault with the exhaust solenoid that is integral to the compressor. You could also have a faulty sensor that is still indicating that it is too low, and therefore it continues to run, trying to achieve the correct height.

You could disconnect a line at the rear shock, to deplete the air. There is a wire bayonet that locks the connection, just turn the bayonet(no the line) 90 degrees and pull it away. With the vehicle on the ground, the compressor may come on to charge it back up. There is no real way to isolate a sensor without a scan tool that reads data. The system could be functioning without the ability to exhaust, and eventually reached a full height condition. The exhaust solenoid is part of the compressor assembly.