I've been jinxed!
Got in my car to come home today and didn't think to touch the aircon controls, just started driving off. Noticed some condensation on the windscreen and looked down to see the fan on speed 2, but A/C light was out. Pressed the button, nothing! Turned the dial to check flow, nothing. Cranked it to fan speed 4 - ahh, working, and look, the A/C light comes on! Back to 3 and it all goes off. Same for 1 - no go.
We've already ordered another fan resistor pack, I'll pull the console apart later to check behind it - but after it stops raining.