Ah, that's because the 102 engine has an electromagnetic fan clutch, which engages at 105deg, I guess.
The fan blades on my 102 have been spot welded to the rotor, so the fan is on all the time. Not sure if this was done by the PO because the solenoid was busted or because we live in the tropics, but it seems to work fine.
Bit noisy though, so might get round to changing it in June when I have to drive the 230 around (300e going in for paint)
On the 103 engine, the visco clutch runs the fan at low speed up to 2000 rpm, at which point it kicks in to high gear and really starts moving some air.
I think the extra two cylinders are there to compensate for the power loss
