I know, summer is coming, what do I need the heater for??
After putting up with 2 days of commuting in the rain, and losing 90% visablilty through the windscreen do to fogging, deciding that opening the windows is the only option and getting soaked by the 'April showers', I decided to actually locate the dodgy wire.
That's always a bit of a problem, cover has melted off the base of the wire at the plug, the inside of the plug had fused together, hurrah for Italian electrical engineering!
Top part of the plug had managed to melt too, black, yellow and pink wires had melted the cable covers and got fused together... GREAT!!
Two hours of swearing, becoming a contortionist, hanging upside down in the drivers footwell and losing loads of electrical connectors somewhere, the plug was cut free, wires re-striped and reconnected in a nice new box (which was originally going on my Suzuki Bandit, not inside the Alfa!!).
Nothing major to report, no melted fuses, fires, smoke or electrocutions from car. All the heater functions now work, air con is now working fine, and the blood is finally re-circulating around my body rather than being stuck in my brain!