Bill,
Maybe not so "easy". This is my unprofessional take on the situation. Current is a function of the device...you don't normally "change" or "regulate" current, you vary the voltage.
Amperage, or current draw is "work done". The heater switch under the dash has a resistance wire in the back..the rheostat. This rheostat varies VOLTAGE to the motor, not amperage.
The less voltage, the slower the motor goes. I think if you plug the figures into the Ohm's Law pie, it will show that the lower the applied voltage, the smaller the current draw through the heater motor..it's going slower..it's doing less "work", it's drawing less current!
The heat the switch is producing is a function of how much VOLTAGE it is regulating. The voltage that the resitance wire is not allowing through to the windings of the heater motor must be delt with somehow..lets change its state..how about into HEAT. Isn't heat the last state of all matter?
Voltage is what you are GIVING it. amperage is what it is USING.
I think this is how it works, but I only made it to the 7th grade.
Stuart
