[Enright]

The actual fan and it's motor are the same units, no matter whether the car has aircon or ATC. So if it's simply a case of a burnt out motor, then there's nothing special about it - it can be easily sourced and replaced from a non-ATC car.

But the control units for the fan are totally different: with aircon cars there is a resistor pack, and this often fails on the lower settings leaving people with just the higher ones.
On ATC equipped cars the speed of the fan is controlled by a transistor pack - it's roughly the same size as the resistor pack so it fits in the same slot, and it looks like a bunch of about 18 x 2" long rods mounted into a plastic block with an electrical connector.

Then of course it could be the main control panel, or simply the fuse to the entire system.

Have you ruled-out the motor itself as the culprit? do you get anything on the display, or any error codes? Have you tried all speed settings including pressing the de-mist button? The reason for this last question is that it MIGHT (although I'm not sure) bypass the lower voltage control to the motor settings regulated by the transistor pack, so at least giving you full speed. You'll go deaf after a short while but at least it'll prove which components are actually still working!

Hope that helps.