With an additional resistor (resistor block) the fan can rotate with 4 different speeds and smooth switching between them.
The auxiliary heater fan resistor is located on the heater housing on the side of the pedal block.
So the block of additional resistors is located (view with dashboard removed).
Removing
Remove instrument panel (see here).
Note. You can do without removing the instrument panel, but in this case you will have to work in extremely cramped conditions, by touch.
By pressing the latches, disconnect the block 1, Figure 14-4, of the wiring harness, unscrew the screw 2 fastening the resistor 3, remove the resistor from the heater unit (interchangeable head Torx Т20, knob).
Figure 14-4 - Additional heater fan resistor: 1 - block of the wiring harness; 2 - screw for fastening an additional heater fan resistor; 3 - additional heater fan resistor
Installation
Install the removed parts in the reverse order of removal.