I don't think it can be serviced, it is generally replaced and Fords been very weak about parts for any of their cars past 10 years old ( unfortunately ). Be sure and check all your fuses, because the clock runs off a courtesy fuse ( includes cig lighter ) or may have its own. You need to remove the panels that border the clock.
Check all fuses associated with the clock. Check your owner's manual for reference. If this does not work replace it by using the following steps I used.
1995 Town Car Digital Clock Removal and Installation 1. Remove clock and housing by applying upward pressure to top of housing and working two front clips out of instrument panel upper finish panel (044A91). 2. Disconnect clock electrical connector. 3. Remove two screws retaining electric clock (15000) to housing. 4. Remove electric clock from housing. 5. To install, reverse Removal procedure.