Help! Resistor on fan switch

[sander17]

Nick,
If the heat sink is getting to 330 deg F.,
then the label "HEAT" seems appropriate. You might want to find a way to disable the position that gets that hot.

[Sav'h Steve]

I started this thread some time ago.

Just yesterday on the Escapees discussion forum I saw a similar discussion with the recommendation to use a heater fan switch for older cars

Try NAPA # HC 6144 Variable rheostat. I haven't tried it yet, but may do that. I understand it doesn't have the 'heat' label.

Let me know if anyone does try it.

Steve

[nickcrowhurst]

Sander17, the high temperature is localized, and at the back of the switch away from combustibles. The dissipated power is probably no more than 15 watts at the highest, and the device is rated to 120. I would imagine it glows red hot at that rate! Any traditional rheostat will dissipate heat in this way. An extra point is that the heat sink is in the air flow of the fan, and is cooled by that. It operates happily for an hour with no localized excess heat. You make a good point, though. I made the mistake of holding the heatsink while testing the circuitry! Nick