I just sorted similar problem of fan not working. After extensive fault finding I narrowed it down to wires that connect to resistor in the fan unit. Basically the connector was burned down and not usable at all, two wires out of five were just held in place by pins on the resistor and heat damaged. So I had two options: one is take it to the garage and replace whole loom (which I believe cost megabucks), and two is somehow make it working again for nothing.
Here is the solution I came up with:
1 press recirculation button. It opens up vent flap underneath steering wheel column.
2 locate resistor then turn it to release and pull out from fan unit
3 take a note of order of all wires, then cut the connector off. Same time on the resistor cut off the plastic that surrounding pins so you can easily work with pins. Only remove plastic that housing female part. Bend pins at about 45degree angle staggering them so you get more room for soldering wires on.
4 solder wires on to pins. A bit tricky but possible. Note of advice: before soldering clean all the pins and apply some solder on them, same with wires. Make sure there is enough room around them to not to short when soldered.
5 push resistor back where it belongs. Job done.
Worzel, October 2012
