after trying to figure out those wiring diagrams for quite a while now, i think i figured out how they work.
the connector is X613
the wires from it go to connector X661
which connects to… (drum roll please) M154 "Ventilation flap actuator" which i believe controls the airflow to the rear seats. will check it out tomorrow.
those diagrams are powerful if you know how to use them. trouble is figuring out how to use them.