What am I looking at on this diagram, and how does this work?

Questions:

1) The dial actuates something (mechanical or electronic) that, in turn, moves a cable. Is this correct?

2) What does the cable lead to?

 

I think the cable is attached to the door in the box that holds the "flapper" that opens and closed to let more or less heat in the passenger compartment.

Pretty sure it's all mechanical.