I wired mine directly to the battery using a relay. The relay is switched from the t-stat and the power ran straight from the battery to the relay with a 30 amp inline fuse, then to the fan motor. Never dimmed the lights, but I was running a 140 amp alternator, too.
As for the boil over....it may be time for a new radiator cap or it may not have been seated correctly. I've had more problems with faulty caps than anything else in the cooling system.....also could be an overfilled radiator.
Glad you finally got it all installed and working!
