I fine tuned the resistor values a bit today. I should have purchased stock in Resistor companies. Turns out for the 12v motor, 12 volt system that a 2.5 plus a 1.5 ohm on LOW, and just the 1.5 on MED is the best combination. I liked the sound of the motor and the fan output best at 6 volts, 9 volts and 12 volts. The heat on a 25 watt resistor is only 140 degrees. Still hot to touch, but not dangerous anymore.
I then took Hot Rod Lincoln and Steve H's advice and spent the day working on a special bracket that mounts inside the heater's air stream using two existing screws so it will not be possible to tell the mod has been made at all. The bracket is easily removable and will come complete with the resistors and wiring harness.
And, because I have been asked to do it, I am also testing a stock 6 volt motor using 12 volt source to see how it behaves using 2 - 10 watt (5 watts bigger than stock) resistors using the same bracket. I will also try the 12-6v reducer to report the differences in these solutions so you can make the call. This will hopefully stop that overheating issue and help explain why they get hot enough to fail using twice the voltage.
