Didn't bother reading the whole thread but thought this would be of interest.
I had the same problem, earlier last summer. Got a 150PD with Climatronic - that means A/C always on.
Started noticing the fans on more and more often, to a stage similar to what you describe.
One day, on my way back from the aiport, got stuck on traffic, quite warm day. Between changing CDs I heard the fans on and off three times and thought "this is definitely not right". 2 minutes later I was roadsided, with my bonnet smoking up and AA on the way. I really panicked as my biggest fear carwise is to see my baby go up in flames.
To cut it short, the smoke stopped, the AA man told me not to worry and just NOT turn the A/C on - "take it to the dealer" he said: "it's your A/C fans".
So I did and some few hundred quid later (out of warranty

), the problem was fixed.
Thought about sharing this.
fck