Audi 4F 3.0 TDI 2006, Air conditioning faulty ( 02071 / 00256 )

Hello,

I have been having a problem with my Audi A6 3.0 TDI (2006) for a few days. The air conditioning is no longer working, and neither is the interior fan. It was working in the morning, but then it stopped working in the afternoon. I have not been able to notice any performance loss or anything like that.

"It's set to 'ECO', but the temperature and other buttons don't seem to have any effect..." After reading, I obtained the following codes:


Address 08: Climate/Heating Control Label file: 4F0-910-043.clb

Part number: 4F0 910 043 HW: 4F1 820 043 S

Part and/or Version: KLIMABETAETIGUNGH12 0170

Encoding: 0000278

Operating Number: WSC 02325 785 00200

VCID: 5BE2916F2F2DA9926A1-800E

2 error codes found:



02071 - Local Data Bus

012 - Electrical fault in the circuit

Environmental Conditions:

Error Status: 01101100

Error Priority: 3

Frequency of Errors: 1

Lost Count: 107

Mileage: 277295 km

Time: 0

Date: 2024.09.06

Time: 19:30:25



00256 - Pressure/Temperature Sensor for Refrigerant (G395)

002 - Lower limit exceeded

Environmental Conditions:

Error Status: 01100010

Error Priority: 3

Frequency of Errors: 3

Lost Count: 107

Odometer: 277297 km

Time: 0

Date: 2024.09.06

Time: 19:37:34


The pressure reading in the refrigerant block indicates a pressure of 0 bar, which seems quite unusual to me. So far, I haven't measured the pressure in the system...


Also, I would also like to mention that work was carried out on the air conditioning system in the spring. In the winter, the capacitor was defective, and it was then only in operation with the fan for about 2 months……

During the repair, the following new components were installed:

- Condenser (Denso) - was defective due to impact
- Klimakompressor (Denso) - had a leak behind the pulley
- Dryer (Hella)
- Drossel /Expansionsventil (Hella)
- Push button (Hella)
- Seals from Hella, VW...

The system was repaired, cleaned, put under vacuum (overnight), and tested. Subsequently, it was refilled. Oil and refrigerant were filled according to Audi specifications…


I would be grateful if you could offer some advice!

Interior cooling fan is broken.

Air conditioning unit (refrigerant) is empty/leaking.

The easiest thing would be to check the pressure of the system mechanically – i.e., using the gauges on the air conditioning service station. Then you would know if the compressor is actually building up pressure.

Often, errors also occur here during assembly: Some compressors come pre-filled with the correct amount of oil, while others have a note in the packaging indicating the amount of oil that needs to be added additionally.

Since the system has been running for 2 months, it's possible that either there was too little or too much oil in the system. The compressor doesn't like either of these situations.


While a data bus error doesn't always perfectly align with a mechanical damage,

Have you ever performed a complete scan of the car, or have you experienced similar errors in other control units? It could also be that another component is causing the bus to malfunction, thus disabling the climate control system.

Hello,
Thank you for your feedback. Yesterday, I disconnected the G385 pressure switch on the air condenser, and the internal fan is at least running again.

The repair was done in early May, and the system has been running smoothly throughout the summer. In the past few weeks, I have also been unable to detect any loss of performance or similar issues. However, it seems strange to me that, according to VCDS, the refrigerant pressure is 0 bar when the system is turned off. In the worst-case scenario, it's possible that the switch is simply defective…

I will next check the pressure of the system using mechanical pressure gauges at a climate servicing station. Unfortunately, I am currently still abroad.

If you need a part number or wiring diagram/pinout here, please feel free to contact me.

Theoretically, it would be possible to trick the refrigerant pressure sensor with a resistor that you plug into 2 of the likely 3 or 4 pins and make it display a static pressure value, and then see if the error can be cleared. In this case, you would need to experiment with a potentiometer to be 100% sure.

As a first step, I would recommend replacing the sensor. This doesn't cost a fortune and you also won't need to refill with refrigerant, as there is a check valve in the line directly at the sensor fitting, similar to a tire valve, so remove the old sensor (just for a short time) and insert the new sensor.

Please note the specified torque for tightening, as otherwise the lines are likely to crack, and you may then need to replace the condenser again depending on the vehicle (because the sensor thread is directly in the line at the condenser).

I have an idea with a torque range of 15 - 20 Nm, but it could also be less! -> I can check this again in the evening.

Hello, thank you very much for your help. I need to apologize for the delay. The air conditioning is now running again. It was a faulty pressure switch. The aftermarket switch unfortunately only lasted a few months....

I have now installed a new OEM from VAG and the system is running again.