Electrical: 1937 Dictator Heater Switch

[Studebaker1965]

Hi everyone,

I’m looking for some electrical advice. I have a 37 Dictator sedan with a factory heater that I’d like to use since it gets chilly in Pennsylvania this time of year. The heater switch is a ceramic rheostat type. I am concerned because the ceramic switch gets pretty hot when the fan motor is running. I bought a new switch from Napa, hoping I could change the rheostat part out and use the original knob, but they are different sizes. The blueish switch is the original Studebaker switch and the red one is the new Napa switch. So my question is about resistance in the switch and trying to use the resistance to tell if the switch is corroded internally. It appears in good shape. I measured ohms when the switch is turned on to max fan motor speed. The original switch measures about 3.4 ohms and the new Napa switch is 2.7 ohms. I’m guessing the difference of 0.7 ohms is not enough to make a difference and that my original switch is good to use? I also assume that the switches are made to get hot, that is why they are ceramic? I have placed a ground from the dash to one of the body mount bolts and measured it so I have a good ground from the dash and heater switch to the frame. The car retains its original 6 volt positive ground system. I have installed all new wiring including new fan motor wiring. Thanks for the electrical advice. It’s a weak area of my knowledge.

Thank you,
Nate

[gordr]

Sounds like you are measuring both switches at the "slowest" setting. "Full blower" should be about zero ohms, and "off" should be infinity. IIRC, those rheostat switches usually start on max, and then slow down with further turning. And yes, they do get quite hot in normal operation, and that is why they are made of ceramic. The new NAPA switch might be a "universal" one, with enough range to be of use on 12 volt systems, too. I believe you should use the original switch; just ensure that it does not come close to other wires when installed.