Okay, here's what I did.

- I hooked up the fan to a variable resistor and 12v power.

- I found that I wanted the fan running on anywhere from 300-500 ohms resistance.

- I dug through my resistors pile and found a 470 ohm 1/4 watt.

- It worked, but the resistor itself felt rather warm to the touch after running a few minutes.

- I didn't have anything in 1/2 watt resistors that was close to the 470. But I did have a bunch of 1000-ohm 1/2 watt resistors. I tried both a pair and a trio of these wired in parallel, and they seem to be doing what I want. The trio seems to do the best.

- The trio of 1/2 watt resistors gets only faintly/barely warm to the touch after running a while.

Does this sound like the proper solution, or do I have anything else to worry about?