3 or four folks on here tried to figure out the ducting a while ago, but no magic bullet. I ran the duct high and the wiper arm grabbed the duct and pulled on it and caused a main power wire to come on and off until you turned the wipers off. We of course found this out in driving rain on a twisting piece of two lane on the California coast, with the ignition cutting in and out and nowhere to pull over. We finally got off the road and I ripped out the duct and left it out for the rest of the trip.