well, on my 92 max (216K and still running by the way)the same problem occured. here is a step by step of the technical procedure to fix the problem with the clock:
1. turn the air conditioner on
2. turn the radio on
3. turn the air conditioner and radio off
4. bang with considerable force with the palm of your hand on the top of the dash above the clock 2 times in quick succession
5. dont forget to curse
6. If that doesnt work, check your watch