Brian is a 1972 crossover bay. These knobs are on the base of the drivers seat and would be operated with your left hand. In 2 years we've never used them, but we are installing new cab mats prior to a new interior. Give me a clue? Any other crossovers have these?
http://www.thesamba.com/vw/archives/manuals/72bus.php Page 41 or if you answer in the affirmative to Keith's question go to page 46
Not sure what they are doing there, but the actual knob end (am I allowed to say that?) on the right is for the fresh air fan, if you are lucky enough to have one fitted, according to my original 1970s manual. In the photo it's identical but underneath the dials on the dash.
The left hand knob sends the heat out of the vents under the walk through floor. The one on the right looks like a choke lever of an old car.
Keith, there's no Ererspacher. Matt, that makes sense! Right, we clearly need that one. LewBlew, we were expecting them on the dash as well. Bus monkey, I'm looking at those now, thanks for the link. We do know that Brian had a well intentioned (we're being kind) restoration and that not everything used was original, correct, or in the right place. Hence the confusion - we can't even trust that these are the correct knob caps!
The one on the right looks suspiciously like a crappy old choke knob - what's on the other end of the cable?