The easiest way i found to make this work. I used the two wire motor from napa, a 1941 switch with heat and defrost. Switch is marked with color dots from memory black is 6v, red and green are wires from motor, yellow is ground. The switch will change direction of the two wire leads to the motor giving you defrost and heat. Has to be run on 6v because the wire resistor will not live long on 12v. Mike