Hi, been reading posts on this forum for a while, learned a whole lot about cars. Finally bought my own 1982 240d and am beginning top dive in. Quick question regarding AC system. I have a dial type temperature switch, when I was pulling the dash off to get to my evaporator I noticed that the switch has a small tube like orifice on the left side with nothing attached. Can anyone help tell me what this is and if anything should be connected because there wasn't anything there?

Thanks in advance!

Hoss