I know so many vanagons that have no working fan to blow the defrost or heated air around the cabin. Somehow the motors seize, possibly from moisture. Removing the dash was one of those scary tasks, the type that if you fail to get the parts back together, you may as well sell the whole vehicle for scrap. At least that is what I thought, now that I have done it, I realize it is not that big of a deal.
Most of these pictures are for my reference to make sure the parts get put back. With the vanagon dash out (you like how I skipped over the hard part?) you can get to anything you want, so it is a good idea to replace and fix what you can. I had a few rust spots to treat. I added as much Dynamat sound deadening material to the body metal as I could.
While removing the heater core assembly I broke a screw, it was rusted solid into the body. I had to drill out the hole and re-tap for a different screw.
My heater core is the type that is fused together (plastic tack welds) in a series of tabs around the perimeter. These must be sliced apart, best keeping as much of the tab material as possible. When I put it all back together I used these tabs, drilled pilot holes through them, and rebuilt using screws.