I'll try to spell this out, remember I have little knowledge, I am still having trouble with wiper door, here is what is going on that I can tell, here is what I have done or replaced, here is where the cruse words go *$##**.

When I turn wipers on, door does not open.  When I pull down on the manual override door does not open.  When I go outside the car, open the door myself (with the over ride pulled down) and then turn on the wipers they work just fine, when I turn them off with over ride pulled down, door stays open, when I turn them off with over ride in the up position, the wiper door closes, if I try to turn wipers on again the door appaers to move a split second and then nothing it does not open.

I have replaced the metal check valve, the plastic filter, the actualator that is located on the back wall of engine compartment drivers side, I had the local chevy dealer ( wrong move aparently) check out the system and they replaced faulty seal in vac canister (seal, plug, boot)  they did that on june 15th.

if I can explain this correctly: when I was poking around (why I don't know) I found a small hose coming out of firewall, there are three (I think) small ones in this area close to the 5 port washer system and also in the area of the wiper door crap I can not see any place that this hose should or could connect to 

Any ideas?  On another note, brake master cylinder was low on the side closest to cockpit, see no signs of leaking by any wheel, brake light still comes on one pedal is pushed hard, also started to leak some power steering fluid.  I feel so inadaquit when it comes to this toy...

Larry

One thing you have not listed above is the vacuum switch that is activated by the passengers side wiper arm. It should have a plunger with 3 hoses on it. Mine was broken and my wipers would not work correctly either. Check this switch and it sounds like, to me, you have covered most everything. 

Larry, I have 72 with air, and have been through the entire vacuum system in my car - lines - motors -etc, and can understand your frustration.

I think first you should trouble shoot why the door will not open/close with the override. This controls just about everything in the system safety - so the door won't squash the arms at the wrong time. The door has an electrical switch that completes the power circuit when the door is open - that's why she runs when the door is pulled open manually - so this is ok. A vacuum diagram from the DOC Rebuild helps tremendously to understand this engineering nightmare.

It could be everything is so crusty, the door motor can't pull it open, or a vacuum problem. This is way to complicated to trouble shoot on the list - call me and I think I can guide you through it better.