Hello, great questions; the air suspension system on the Town Car is made up of several key components: a control module, a compressor, a dryer, air lines, height sensors and the air springs themselves. Your concern, from my computer point of view and experience at least, sounds like you might have a leak at the dryer. The compressor creates air, the dryer takes the moisture out of compressor created air and routes the air through air lines to the rear air springs. If you have a leak, the compressor basically works its tail off to keep air going to the rear springs, to keep them inflated. Since the compressor is basically an electric motor, eventually it can't keep operating continually anymore, and it shuts down. This along with a leak means your springs sink down to the ground, and you have the resulting rough ride from a rear suspension sitting on the ground essentially while driving. Compressors are pretty darn expensive, but you may need to replace that at this point. The compressor alone is around $700 for just the part, and the dryer is nearly $300. Then you have labor, and you truly must visit a technician with the specialized knowledge of the Ford / Lincoln air suspension systems. It's pretty important. One further note: as you have had your rear springs deflated, you will need to check them for damage as a result. Cracks and leaks can occur especially due to this abnormal driving condition, AND in addition the fact the springs, if they have never been replaced, are now 14 years old. Remember - they are rubber, and rubber dry rots over time, causing leaks. Good luck!
