I have a '98 Navigator. Yesterday drove to work with no problem. Went out about an hour later and the rear end was just about sitting on the tires. Started it up and drove around the parking lot thinking the compressor would kick in and level it but nothing happened. Checked the fuses and they are ok. There is also no check suspension light on. I haven't had time to crawl underneath to look for anything obvious. Anyone have any ideas?...thanks, Doug