Fixing an A/C system is an expensive proposition. Are you going to do all
this yourself? It is much cheaper that way, as licensed folks need to do it
proper. Your system will need to be emptied and refilled by them. The
refrigerant needs to be recovered and returned to the vacuumed system. Add
to this, any repairs. R-12, 134a? Got to buy this, too. 134a is high now.
Probably best to switch over to 134a at this time-$$$.

The condition of your system and how much you like A/C need to be considered
here. Rubber hoses in the Vanagon seem to generally hold up well. They
should last a number of years more in your '84. Replacing one hose is a good
idea. Your old fittings on either end will be reused. Your new hose will be
a barrier hose, as that's all that is available. The barrier keeps 134a from
migrating through the hose wall. Hose is about $3/ft. The existing residual
oil in the old hoses will prevent 134a from migrating through the hose if
you convert over. That hose is not too difficult to snake out from under the
Vanagon. Where would yo get a vacuum pump?

The hoses that attaches to the compressor have fittings that are barbed.
They work great! They don't leak often. They slip into the hose and are
clamped with hose clamps. See them?  An alternative repair is to get a
junkyard hose and cut it about 2ft from the compressor. Buy a barbed splicer
from an A/C specialty shop and splice this section into your old hose.

If you are not going to do this yourself, it will be expensive, and a new
hose will be required. Hope you can find someone who will work on your
vanagon. How big is your leak? That is a very important question. Maybe you
can live with it. Your a/c system may not be worth fixing. Get an estimate.