It boggles my mind how the D2 manages to blow different temperatures from different vents when it mechanically does not have the ability to do that
Centre vent excluded of course - that's a whole load of problems in itself!
Mine blows roasting hot from the driver's side dash and floor vents but the requested temperature from the windscreen. It only has temperature control in the heater cores so how does it blow two different temperatures at once?
One of my projects this year is to figure out how this arcane and frustrating system actually works so I can stand a chance of fixing it! I have a complete hvac system out of the car so I can study it in detail, and part of the project is redesigning the valve block.