what size resistor ????

aussie merc

Well-known member
the fan switch resistor has failed in my 39 does anyone know what size/value the it was so i can repair the switch Thanks
 
Are you asking for the ohm resistance and wattage of the small resistor mounted to the rear of the heater blower switch?
 
terry yes ignition ballasts i got boxs of em but the little suckers on the fan switch their a bit of a mystery
 
I believe the resistor is used to put the fan motor on slow speed, If it is open circuit the slow speed will not work, the motor will stop.
 
Terry >>I believe the resistor is used to put the fan motor on slow speed, If it is open circuit the slow speed will not work, the motor will stop.>>>


Yes, my understanding too. If you bypass the busted resistor with a wire, the fan should run at full speed.


6v fans typically draw ~8 amps or ~50watts at full tilt.


To cut the power in half you'd need a ~1 ohm resistor with a ~25 watt heat dissipation rating. Like an ignition resistor, they can get quite hot.
 
My Ford heater switch measures between 1-1.5 ohms. Even though it is NOS, the switch is put together by compressing the connections which makes the actual resistance fluctuate by the contact resistance. If Jack's current consumption is cut in half during slow speed operation, then the wattage is 4 times 4 times (1-1.5) or about 16 t0 25 watts so the conclusions are consistent. If your resultant speed is not what you like, modify the resistance a little around these values.
 
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