Is this could be the real culprit.
Pressure Sensor via Junction Box
The refrigerant pressure input signal is a direct junction box input signal and is relayed to
the IHKA via the K-CAN. The IHKA requests actuation of the auxiliary blower by the DME
(ECM) depending on the refrigerant pressure.
The IHKA determines the relevant A/C compressor load torque on the basis of the input
signals from the pressure sensor and the compressor speed. The DME (ECM) control
units are notified of the load torques by the IHKA and used by the DME (ECM) as input
variables for actuating the electric fan.