Thanks to Max and Alan, who responded and helped clear some of the mysteries of the front blower housing in my 84 1.9 van. And now that I have removed the blower motor, I have a few tips for anyone thinking of doing the same job in a van like mine. (I'm new to the Vanagon world and don't know anything about fans in other models.)
Heater fan replacement tips:
1. Don't do it! First consider selling or trading the car. Or forking over a lot of dough to an experienced VW repairer.
2. If  you ignore 1., expect to put in a lot of frustrating hours hunting for hidden clips, secret screws and other tripping points not mentioned in the official repair manual . 3. Also realize that the manual does not tell you the most important fact: the entire box must be removed, or pulled it well back from the front wall of the car before you can find all the hidden clips, screws, etc. And of course, you must start the job by removing the dash board.
 4. As Max says: "Check that heater core while you're in there. They don't tend to leak like the rear ones do, but you don't wanna do this job it twice."
5. Install the highest quality replacement motor you can afford -- for the same reason stated above.
Tom 
hedgehouse2@verizon.com