Heating for Jag MK IV DHC

Hello,

I tried to understand how the heating and demister of a MK IV works… You have the heating unit under the dash with 3 connections : one for the hot water from the engine (with a tap), one for the cold water to the engine and one with a hose going to the demisters of the windscreen. But my question is where to connect the hose coming from the air inlet in the middle of the windscreen?
thanks for your help

The air hose from the vent just pokes loosely into the box that surrounds the heater under the dash.

Peter