I don't know if I really get your point,
but as for our raditor fan, it has two speeds, hi-speed always trigger
by turning AC on, or extremely hi collant temperature while traffic jamed.
The GTI's faultly fan has been a known issue here in Hong Kong,
The problem is that the plastic frame inside the fan motor
has melted down, so it jamed the contact pin movements.
Symptom : the fan won't run even temp. above 100 degree, but if
you knock the fan motor hard, it comes on.
Most of our mates have second unit of raditor fan already, I have 3rd unit
though.(from China VW).
I think the original fan motor design is a fault, not suitable for hot
weather.