Radiator fans run from start to stop

[samach]

Hi,

My radiator fans turns on the minute the car starts and they keep spinning until the car is turned off. This happens irrespective of the engine being hot or cold. Did a scan and saw these two faults. Not sure how they can be related:

1 Fault Found:
4339 - Implausible Data Received from HVAC Control Module (J301)
U0424 00 [00100111] - -
[Invalid Data Received From HVAC Control Module]
Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 2
Fault Frequency: 1
Mileage: 333157 km
Date: 2025.05.17
Time: 10:53:54

Engine speed: 0.00 /min
Normed load value: 0.0 %
Vehicle speed: 0 km/h
Coolant temperature: 37 °C
Intake air temperature: 19 °C
Ambient air pressure: 1010 mbar
Voltage terminal 30: 11.980 V
Unlearning counter according OBD: 40
Crankshaft speed (RPM): 0.0 /min
Vehicle speed: 0.00 km/h
Accelerator position: 0.00 %
Vehicle voltage terminal 30: 11980 mV
Sig Reset Env x Id-Bits 0-7: 0
Sig Reset Env x Id-Bits 0-7: 0
Coolant temperature: 37.0 °C
A/C compressor torque: 0.0 Nm
--------------------------------

Address 08: Auto HVAC Labels: 4F0-910-043.clb
Part No SW: 4F0 910 043 HW: 4F2 820 043 L
Component: KLIMABETAETIGUNGH20 0170
Revision: 00000034 Serial number: 00000030536856
Coding: 0001044
Shop #: WSC 02325 785 00200
VCID: 5BE265DF2F215E02BA8-800E

1 Fault Found:
00256 - A/C Pressure/Temperature Sensor (G395)
004 - No Signal/Communication
Freeze Frame:
Fault Status: 01100100
Fault Priority: 3
Fault Frequency: 1
Reset counter: 38
Mileage: 333157 km
Time Indication: 0
Date: 2025.05.17
Time: 10:53:51

I first suspected coolant temp sensor but the reading looks OK. Then I suspected the Fan control module but the output tests in VCDS were able to switch the fans on and off during the tests. So not sure what could be wrong here.
Does the A/C pressure sensor has an impact on the radiator fans? My A/C has not been working for a long time and the A/C Pressure/Temperature Sensor (G395) error has been there for a while, but the "fans constantly ON" issue is new. The Implausible Data Received from HVAC Control Module (J301) is a new fault, could that be the cause? TIA

My car: 2010 A6 C6 facelift 2.0 TDI Engine code CAGB

[mickeybo]

The cooling fans on your vehicle has to be controlled so that allowes the engine to maintain a contant tempature.The 2 temperature sensors 0nyour vehicle has to be checked out to allow the ecu to control your fans

[samach]

The cooling fans on your vehicle has to be controlled so that allowes the engine to maintain a contant tempature.The 2 temperature sensors 0nyour vehicle has to be checked out to allow the ecu to control your fans

Thats what the output tests on VCDS do. When you run the tests, I can see the fans get turned off and then turned on again. That would indicate the fans are controllable.
Which 2 temp sensors are you talking about?

[Crasher]

Can you post a full car scan and include the VIN?