Ozz,
That is a good idea. I know that the fan is not on the same breaker as the AC because when the AC trips, the fan still works. Maybe the fan is on a circuit that is loaded with other light fixtures. I bet putting it on its own circuit would solve it all, but I'm a civil engineer not an electrician.
Tim Marshall
2004 3670RL Montana
2002 F-350 powerstroke diesel