Resisters are supposed to lower the voltage...Make sure your fan switch is at its highest setting, and then check the voltage at the motor...It should then read 12V...Even at 6V your motor should spin, check the connections, but it's probably your motor.
Replacements are readily available at the parts store of your choice for low bucks.
Good Luck!
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68 El Camino...Slow, Much Work Required
98 Z28...Fast, No Work Required
Goodfellow AFB, San Angelo, TX -- Where? That's what I said..