Ok. This is what I did.

If you use a long screwdriver you can actually insert it thru the vents and push down the flap and check if you get air blowing.

Inside the central vent, there is a screw. I removed it and pull the left side of the vent just enough to insert a stick of wood using some pliers to lock the flap down. It's a little complicated but after some trial I got it locked.

I wanted to remove the hole vent but It looks like you have to remove the airbag cover to acces a screw on the right side of the vent.

BREWTO: we would really appreciate if you tell us how to test the vacum system without removing the airbag.

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Juan
1995 E320 Sedan
2008 Ford Escape
RC Helicopter