The Stovebolt Site Forums The Shop Area The Electrical Bay Heater Motor

Hi everyone,

The truck is a 51 3100. Just a quick question about my heater motor. It is the standard heater and I have high speed on the blower but not medium or low speeds. What should I be checking first? As the evenings are getting cooler I would like to get the heater working properly. It puts out plenty of heat with the fan blowing on high.

Thanks for the help!

You must have a three speed switch. Except for hi speed, the switch adds resistance to the circuit. Usually the ressitors are little coils that get red hot when in use, ie medium or low. Either the resistors are blown or the switch is faulty. I found the new ones melt on anything but high. I am still running a 6 V system.

Yes there is a resistor attached to the switch. Still running a 6V system too. Should I just not worry about it and run it on high?

That would definitely be my suggestion. Like I said, the new ones that I tried just melted.

but i see that there are 6v and 12v motors available. mine is a delco 5947688, and since the heater came from a 6v vehicle, i'm assuming that it's a 6v motor. but it sure runs on 12v!
did the original switches have speeds? are complete truck wiring schematics available for the '48-'53s?

I would assume that my 3 spped heater switch is an original. If you are running a 6 volt motor on 12 volts, you need a voltage reducer. They sell one that is in a metal case and is made to be attached to metal to disapate heat.

oh yeah, reducing the voltage isn't a problem, but since you guys are mentioning melted resistors/only high speed, then something is amiss. i'm also seeing a motor that's listed for a delux heater and a switch for same, and since all motors aren't designed to be variable speed, i'm wondering if using a resistor is a viable solution. bec burning resistors is an indication of incorrect amp draw

and then i found a mention of mounting the resistors in the air stream to help keep them from overheating