Sorry I am late to this but am new to the forum.  My wiper door opens immediately upon starting the car and closes in 10-15 seconds.  It was opening also upon heavy accelleration as well but I was able to stop MOST of that by replacing the rubber plug in the actuator.  I am sure that the opening at start up was not the way it was meant to work originally so what is causing the opening at start up.  It is no big deal but it is causing unnecessary wear on the unit.  Not to mention it just bugs me!

Thanks!

Tim-

 

I had the same problem many years back, it turned out to be a bad control valve that is located passengers side cowl. You can see it if you look down the vents. It should have a plunger type switch with 3 vacuum lines going into it. When I got my car in 1990 the plunger wasn't there anymore. Also, make sure your vacuum canister is working properly.

Thanks!  I'll check that again.

Tim-