I can't believe your having those problems. I'm running the HotRod Air system (derale) with a 65A alternator and haven't had any charging problems at all. Also run Halogen lights and decent 100W sound system. Maybe there is a short in the fan motor, weak battery, weak ground, or faulty wiring causing elect. resistance somewhere. Have you tried a larger battery, bigger cables, check all cable and wire conections, etc. My fan runs through a thermostat and relay system with 10guage wire and 30A fuse that connects directly to the battery post on the solenoid.
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