When it is about to have the fan go on, the static starts... often the static stops once the fan is on (though, not always).
Sounds like the fan is controlled by a thermostat. Automatically turns on and off?
I still think it is a faulty wiring issue, poor electrical connection, or a faulty contact.
The thermostat could be a line stat or maybe low voltage that controls a relay that turns the fan on and off.
Best thing to do is call a service tech and have it checked out.
Be thankful the static is not an intermittent problem where it only happens once and a while. Those are the worst to diagnose. You want it to act up when the tech checks it out.
Jim