Schocki

If the temperature circuit is interrupted, full cold or hot will be available only. The slider on the HVAC controller overrides the temperature sensor logic via microswitches in these two positions.
The transistors are the most likely cause for a non functioning temperature flap motor. Mine failed during the summer in Spain and it was not funny. But good news: it is easy to disconnect the lever arm from the motor. The flap automatically "falls" to the full cold position. Bridging Pin 2 (red) and Pin (black/red)on the smaller of the two connectors at the motor activates the heater valve solenoid (closed position). At least it's cold again...

The transistors needed are 2x BC327-25 and 2xBC337-25. Below a picture of the transistors and their positions on the CB.