3   A/C ducting.     I fitted the cab roof section of a '84 vanagon A/C
ducting to the board type roof liner in my Westy.      This was tricky as it
did not want to fit well and threatened to crack.     I reinforced it with
epoxy and glasscloth inside the ends and left it a little on the loose side
and now it works well.
I ran a duct from the rear unit straight into the centre rear facing
ductwork
and made a baffle to close the gaps.        I am amazed at how well it
works!
Before, I would have to have the A/C on full blast and put up with a light
draught on my back as well as a jet like noise but now I can get an
effective
frontal airstream with the fan in its lowest position.
The duct I use is made from 2 lengths of white vinyl guttering down pipe
which are 2 1/2 inches square.   They are attached side by side and fit into
one of the two bigger diffuser outlets of the rear unit and run straight
into
the front roof unit.
I can remove them in seconds when I want to put the roof up and I can easily
pop the diffuser back into the hole in the rear unit.
I must say it is not particularly pretty and if anyone has done a nice
professional looking duct, I would love to see pictures.