1999 Lincoln Town Car

Could be an actuator for the a/c system try this and see if any error codes come up.
Run the self diagnostic test on it by turning the key to on, then press off and floor at the same time, then within 2 secs, press auto, If there is a problem a trouble code will appear on the display. To exit self test, press the BLUE, cooler button this also retains error codes, To erase codes and exit, press defrost, choose one of these before you power down the system. Test with engine at 120 degrees or more, and cabin between 40-90 degrees. Post any codes recorded here and I let you know what's defective.