What is the gizmo box under my 86 Camper GL's rear bench?  It appears to
be 'stock' and it made by VW/Audio.  There is a valve that seems to turn
on/off, and some electrical wires going into the box.

Is it air conditioning?  Is it a heater for winter or perhaps a heater
for camping?
 I'd appreciate help to find out what this does, and also how to use it!

Thanks,
Shawn
'86 Camper GL
'73 Campmobile