I have read a lot of talk about the vents in the rear of the car and wonder if there is a way of testing them?

 

I do find that the doors will not close unless you shut them with some force, my old Mondeo used to close the doors with the lightest of touches.

The easiest way to test them is to listen for the clap noise they make as they close a split second after you slam a door or especially the boot. 

Could just be an adjustment issue.  Mine shut very easily.

What vent thingies.....?