The fan control is not variable resistor controlled so thats not an issue. I have a problem with mine but when it stops working I just move a cable at the fan motor itself (I know which one to move now) as I have a loose connection. It normally works fine for months (had to do it just once last year) so I've never got around to fixing it. Have a look around the fan, put the fan on and give the cables a slow 'wiggle' to see if it springs to life. Be carefull though it may only be 12V but it's the Amps that kill you. If you find nothing that way try taking some voltage measurments at the motor.
It may only be 12V but it's the amphere that kills you!
3Ltr V6 ES9J4S D8
As lecky said it's always worth checking the wiring around the fan, I had a similar problem with mine that I cured by banging the glove box as hard as I could, finally packed up all together so I had to have a proper look. Turned out I had a bad earth somewhere which had cooked one of the connectors. Haven't traced the earth fault yet as I just swapped the connector for a big terminal block I had in my tool box, will attempt a proper fix when the weather improves
1996 1.9 TD LX (Gone but not forgotten)
2003 2.2 HDI SE