I wouldn't know where you would find it or how to replace it, but all that door does is stop objects from getting into the ventillation system when the hood is open. When the hood is closed, that area is sealed and filtered through the cabin air filters on the hood. Until you find another replacement, just make sure that nothing goes into that hole when the hood is open.

 

Thanks.. if I know the name of it maybe I could look it up

 

This?

"Microfilter clean air channel"
64-11-8-390-380

 

This item is pushed open when the hood is closed down and it is the ventilation air intake, It closes when the hood is opened to hopefully stop mechanics dropping items into the air intake.