easy: I [current draw of motor]=E [12V]/R [the resistance of the motor windings] translates to P=IxE
power in watts [like yer portable electric heater, which is just a resistance wire element], is what makes heat, and that's determined by the current the motor uses to run times the voltage you have - the slower you run the motor, the more current has to be dumped someplace else, which is the resistance unit on the back of [or inside] the switch, and that piece is quite small, hence can get red hot
here\'s the repro switch - note the ceramic backing - here's the back of
an original switch - the coil of wire is the "heater element" that gets rid of the extra heat, which is why part of the switch assembly is ceramic - newer style switches have better ways of dissipating the heat
Detroit didn't design it, God did - just the way electricity works!!
Bill
