Some thoughts...
Some cars don't have the fan wired to the ignition. You hear the fans still running after the driver has locked the car and walked away. Don't remember which cars. My hybrid does things while parked in the garage - a bit disconcerting at first - did I leave something on?
The stock 1950's generator may not be able to keep up with an electric fan while at idle. While at idle, with my heater fan going, my truck would stall as the voltage dropped and the ignition cut out. (I solved the problem by installing a 12V to 6V converter for the heater fan). So, I suspect than an alternator may be in order if you use an electric fan.
