im having the same problem with my 93. the temp control unit (with the fan control and temp control and vent control) i think goes crazy. i can turn on the ac and the led will come on, but if i hit a bump it will flicker. also when i turn my rear defrost on, sometimes it wont come on, sometimes it comes on and i cant turn it off. so at least with my car i think the controler is fucked up