A good preparation is half of the work...
Now the missing link and we can go take a look ...
Basicly you want a control unit for the temperature and air flow in you car.
I think you should start defining your needs. Something like you already said bottom vent, top vent, AC on/off, ... but then all of them. Not only this and that but concrete, for example speed and position of top vent, switch or push buttons for AC on/off, temperature higher, lower and so on.
Then check the hardware you already have motors, sensors, command buttons, ...
Finally describe the functionalities you need.