I have just removed my fan from the fridge/freezer in anticipation of ordering a new fan from the bosch eshop
I removed the two screws from the top lip of the freezer compartment and the two screws on the back wall. the large white plastic housing (with metal tubing inside) slides out, but remember to unplug it's cable from the back left hand corner. The large metal tubes with fins remains attached inside the freezer. Then, after unscrewing the two screws on the fan, I managed to rotate the fan housing clockwise and slide it out. It's a tight fit, but it will come out of the freezer with some patience.
I'm hoping this is the only thing wrong with the fridge, but £70 for a replacement fan unit seems a bit steep!
Sam Dineley, July 2009