Switch question for rear defroster

The problem is I have no idea whether the resistance is correct. What you need is one of these hoarders on here LOL to measure one they have that is for the defroser

Used to be parts stores sold "volt drop" various names intended for 6/12 conversions. If memory serves, one popular "round" device was designed to drop 12 to 6 WHEN USED with a 4A load. The motor load and the resistance both determine how fast it will go, along of course with supply voltage

The put this simply it's called "Ohm's Law"

JC Whitney sells those. Not sure if the motor pulls enough amps to lower the voltage to make a difference. bUT a ballest resistor creates heat to drop voltage. Not hot enough to damage but I’m going to try that route first before since I have 1/2 dozen in the shop. Thank you for the Info. Different way to look at it.
Joe