Hello, i swapped engine to my audi a4 b5 and turned on on standalone ecu. I need litle help with turn on the a/c.

In electrical diagrams climatronic panel is connected to ecu (m3.8.3) with grey/black cable (pin8 in ecu to pin 12 in climatronic panel) but i don't have idea what type of signal is this. I think this is nessesary to have the a/c function.