I have a circuit driving a mixing solution slightly different then conventional controls. For instance I can control the vent and floor in any mix combination. The Defog is completely separate. The fresh air or recirc is completely mixable.
I made a P2 T2 valve for the cooling tubes so no pump is needed. I use an electric valve to turn on the heat. No I don't recommend someone going through all of this but it is an example:




