I have a 160 PA-24-250 and the defrost vents are simple holes in the instrument panel cover with some scat hose connected. This blows a narrow jet of very hot air directly onto the windshield which has caused deformation and cracks to appear. I am planning on replacing the windshield next annual but also want to change the vents so this doesn't happen again.
The panel cover is quite flimsy and an alteration would be very simple thing. Has anyone done anything like this? I was thinking of fabricating something more like a slot with some vanes to spread the air over a larger surface area so that it might slow down and cool before reaching the plastic windshield but if there is something already out there...
William