My fan just stopped completely with no sign of it misbehaving before - and just before this years hottest weekend. Couldn't face the weekend with no A/C so thought I'd check it out.
First I checked the heater blower fuse #76 - this is not on the main fuse board, but you need to remove the trim panel under the glovebox - just slide forward toward you. Look for two pairs of big leads and the large fuses are on the other side of the carriers - you can't see the fuses. Fuse fine so I decided to pick up this thread and change the final stage resistor and see what happened
These are Superb instructions - those with RHD note Quicksilver28's post - you need to be in drivers footwell if RHD and the FSR is about 2" above and forward of the screw you take out for the console side carpet removal.
Sorted - 50GBP for part, 15 minute job. Done.