I have this issue and its the only reason I could curse my car for having an air con... It is indeed impossible to remove the fan unit without draining the air con and separating the connector to the intermediate unit where the evaporator is. I've been trying things all day... with a lot of brutal force its possible to push the intermediate unit away from the fan - not enough to get the fan out, BUT enough to unscrew the air recycling flap motor box from it
I removed the windscreen wiper motor which helped a little, and tried removing the wiper mechanism, which was impossible - apparently it can only be removed after removing the intermediate unit. Somehow I also managed to remove the scuttle panel.
Anyway, the mechanical stop and gears of the flap itself are OK, but inside the motor box one gear lost all of its teeth and another has lost two. So if I'm lucky, I can find a good box on
and just take out the gears (replacing the whole box would be very difficult, the cable is taped together with others and goes behind the intermediate unit).
By the way, the motor gets current all the time the ignition is on, not just when its moving. There is no stop detection - the box has 3 wires, +12V from the 20A heater fuse (A1), GND (C1), and a direction selector wire (B1), which can be left open for one direction and pulled to ground for the other. The motor is connected in series via a 51 Ohm resistor, so when it reaches the mechanical stop it simply blocks and 0.1 A continue to flow. Its probably advisable to change the resistor to something higher, as it seemed to me the torque at the end of the gear train was a little overkill, hence ruining the gears...
If anyone managed to take out the fan unit without draining the air con please let me know the trick... I really dont want to drain it.
Some pictures are attached