(Posted on behalf of Tony Flisch because of a site hiccup)
The air flow enters the ABS tray at the back – furthest from the screen – and flows through the compartments to the front and up through the slots in the plywood. It requires an airtight connection between the shelf and the tray as well as the periphery for this to work.
My problem was, as the ply was soaking wet and the tray too, the air was passing through 100% humidity – especially at the passenger side and condensed on the screen – the opposite to what it’s supposed to do!
cheers
Tony