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Radiator resistor assembly - what's it do?

9 July 2008
Mineral, Va.
I've been staring at that huge resistor assembly mounted up on the top of the radiator, trying to figure out what the heck it does and why it is so huge. I'm apparently never going to figure it out so will ask here - what's its purpose and why is so big? BTW, it's a 97, 6spd if that makes a difference.
The cooling fan has 3 speeds, off, low and high. Off is easy no power and high is easy full power but to get low speed the power for the fan motor goes through the resistor. The size of the resistor has to do with the power dissipation required; motors take a lot of current so there is lots of heat to dissipate so the resistor needs to be large so it can do its job with out burning up. As you can see there is a heat shield over it so it does get hot.
Brian, thanks, I would have never figured that one out and would have never realized the fan had multiple speeds but guess that explains why there is only one fan versus multiple ones like a lot of cars resort to for increased flow.