AC Climate Control auto problems

[merlock]

I have a 2000 Porsche 911 Carrera Convertible and there is an issue with the climate control I'm hoping to get help with. The part is officially called the "Switch Assembly for A/C & Heater Control" with part number 996-653-101-03 .

On the climate control, the max fan speed is represented by 12 "bars" on the display. When the climate control is on "auto", even when the target temperature has been reached, the fan speed never goes below 4 bars (the equivalent of ~33.3% fan speed). The only way to get the fan speed down to less than 4 bars is to use manual mode.

How can I change the behavior such that when the climate control is in auto and the target temperature is reached, the fan speed automatically reduces down 1 bar (which would be the equivalent of ~8.3% fan speed)?

I asked a local Porsche dealership to ask Porsche headquarters about it, but the response wasn't helpful. They said,

"Since this is occurring with the system in 'Auto' mode I would not find this to be an issue. This is especially true if the system is responding properly to correct the cabin temperature to the selected value. Unfortunately, to take this further, I do not have access to any other documentation of the HVAC system operation than is available to you, nor do we have any 9x6 vehicles here to compare with."

I've already tried the following and it seemed to make no difference:
* using another same model number climate control (it was used, so it could have also been bad for all I know)
* replacing the "Series Resistor for A/C and Heater Blower Fan" part 996-573-923-00

Another issue which is unrelated, when in auto mode, air isn't diffused. (when in auto, air only comes out of the front left, front center, and front right vents but won't come out of the top vents or bottom vents.) I would like to have the air come out of all vents when in auto mode so it is more diffused.

If anyone has any idea of how to reprogram the climate control or resolve this somehow, it would be greatly appreciated. It would be great if there is a way of changing the behavior without having to open it up and modify the circuit board, but as a last resort I would be open to having an engineer do that. Any detailed info of the circuit board inside the climate control unit, (especially how the ic is programmed) could be helpful because I could maybe have an engineer figure out how to reprogram it if I had more to go on and share that info with others if they want to change the way the auto function behaves.

Thank you!