This is courtesy of the Lincolns Online tech forum:

HOW THE AIR SUSPENSION WORKS

The system consists of:

A compressor with built in vent solenoid and air drier
Compressor relay
Two air springs and spring solenoids
A height sensor
An on/off switch and a control module

The control module also receives inputs from the courtesy light switches and vehicle speed sensor. If the speed sensor isn't working then the air suspension will not function correctly.

When the car is started the air suspension module will immediately raise the vehicle to trim height if needed. No venting is allowed for 45 seconds after starting, so if the vehicle is high it will remain high for at least 45 seconds. Venting is also not allowed when a door is open. When the car is moving the module uses a 45 second averaging procedure to control trim height. This means that unless the module receives a high or low signal continuously for 45 seconds no adjustments are made. If the car is stopped and a door is opened and closed an immediate trim height adjustment will be made.

If during a lowering or raising procedure trim height cannot be achieved in the "time out" period, the "Check Suspension" light will illuminate and the air suspension module will turn off. When the ignition is turned off and back on the air suspension module will return to normal operation and try to maintain trim height. The "Check Suspension" light is also illuminated when the air suspension is switched off using the on/off switch.

After switching the car off the air suspension remains active for one hour. From 0 - 59 minutes only venting is allowed providing all doors are closed. At 60 minutes, if trim height is low, the module will raise the car to trim height or run the compressor for 23 seconds if this is not achieved. At 61 minutes the air suspension system is switched off.