'89 569SL A/C control

[rjk]

I removed the vertical console plate to get at my radio easily and found one of the A/C vacuum lines was disconnected. There are 2 lines running to the recirculation (upper) switch which has 3 connections labelled A, B & C. The one still connected is attached to "C". Which one does the other line go to, "A" or "B"? I lean towards "A".

On another note, when the A/C switch/control module goes bad, is it fixable? Is there a particular component that goes south? I'm not afraid of electro-mechanical devices and know how to wield a soldering iron.

Thanks in advance...

Oh yeah, it's a 560SL, fat-fingered the 9.