T4 Climatronic: Climate Control System

Hi!

I'm having a problem with a T4 long wheelbase van equipped with Climatronic. Specifically, I can't adjust the temperature or fan speed for the front and rear vents.

"If I unplug the white connector from the Climatronic control unit, I can adjust the temperature and fan speed."

I've already replaced the blower motor and the blower motor control module, as well as the resistor for the rear fan.

Error memory is empty.

"When I try to make a diagnosis using the Stellglied function, I receive a message indicating that the function is not supported."

Does anyone have a suggestion for me?

Best,
Chris