lesabre dash lights

Have a 94 lesabre and the radio a/c lights blink when headlights are turned on at night. During daytime lights are dimmed so I can't tell if they are blinking. Thought the control was in a/c controler (dimmer) but problem continues after replaceing controler (for a/c problems). Any ideas? bumps in the road have not effect, they dimm and brighten even when the car is parked.

Maybe you should try to post this in the Buick forum.
I would say that it could possibly be a loose connection or a relay. are the headlights dim at all?