Audi A6 Air Conditioning Repair
When Mr P brought his Audi A6 to Smith’s of London in Croydon, he explained that the air conditioning had stopped producing cold air. Thinking it might just need a re-gas, he asked our team to take a look while the car was in for its scheduled service.
During the service checks, our technicians confirmed that the refrigerant level was correct and that the system was sealed, yet the air conditioning still wasn’t working. That ruled out a simple top-up and pointed towards a deeper fault within the electrical communication network.
To investigate properly, we arranged for Mr P to return for a dedicated diagnostic session. When he did, our technicians used official Audi wiring data and system diagrams to trace why the system wasn’t communicating with its G395 pressure temperature sensor.
If your Audi A6 AC is not working, read on to see how our structured approach at Smith’s of London uncovered a LIN communication sensor fault and delivered a lasting Audi AC wiring repair to restore full cooling performance.
Audi A6 AC Not Working: What the Initial Tests Showed Us
After completing the service, Mr P returned to Smith’s of London in Croydon so our technicians could carry out a detailed investigation into his Audi A6 air conditioning fault. During the earlier checks, we had already confirmed that the refrigerant level was correct and that the system was sealed, but it still wasn’t producing any cold air.
With a re-gas ruled out, we knew we needed to look deeper into the system to understand what was preventing it from working. The first step was to perform a full system scan to check for stored communication faults.
This returned one fault code:
00256 – Air Conditioning Pressure/Temperature Sensor (G395): No Signal/Communication
The G395 pressure temperature sensor plays a crucial role in the Audi A6 air conditioning system. It monitors both refrigerant pressure and temperature, sending that data to the control module so the system can run safely and efficiently. If that signal is missing, the compressor won’t engage — a built-in safeguard against damage.
At this stage, we couldn’t yet tell whether the fault was due to a failed sensor or a problem in the wiring between the sensor and the control module. The next step was to investigate further and trace where the communication was being lost.
The Discovery That Revealed the True Cause of the Fault
With the first tests complete, the next goal for our Smith’s of London technicians was to locate where communication between the system and the G395 pressure temperature sensor had been lost.
Using the Right Data and Tools
To move the investigation forward, our technician accessed Audi’s official wiring diagrams and technical data. These showed exactly how the G395 pressure temperature sensor receives power, shares its earth, and communicates through the LIN network — the pathway that allows the air conditioning system to exchange pressure and temperature data with the control module.
Using this information, we connected an oscilloscope to the three wires at the sensor’s connector:
- Power supply: Voltage present and correct.
- Earth: Ground connection located.
- Signal line: No LIN communication picked up.
This confirmed that the sensor was powered but unable to send data to the control module, suggesting a break or fault in the wiring between the two points.
Comparing Signals Across the System
To verify the result, we tested another sensor on the same LIN communication line. The second signal appeared normal, confirming that the control module and the rest of the network were functioning correctly.
That meant the issue was isolated — the fault lay somewhere along the wiring route between the G395 pressure temperature sensor and the main junction of the communication circuit.
Tracing the Break
Following the wiring route methodically, we tested at several connection points between the control module and the front of the car. The signal remained stable until we reached a connector behind the passenger-side trim, indicating the fault was further forward in the loom.
That section of wiring runs over the nearside front wheel arch and beneath the headlamp. When the protective sleeve was carefully opened, the problem became visible: corrosion within the wiring had damaged the copper strands, breaking the communication link.
That single fault had silently interrupted the signal between the G395 pressure temperature sensor and the control module, leaving the air conditioning unable to activate.
With the issue identified, our next task was to repair the wiring and restore full system communication.
How the Wiring Fault Was Repaired
With the cause of the problem located, our next step at Smith’s of London was to repair the damaged section of wiring and restore proper communication between the G395 pressure temperature sensor and the air conditioning control module. Before starting, we discussed the repair plan with Mr P and explained how the fault would be corrected.
Accessing the Fault Area
The affected wiring was found within the harness that runs across the nearside front wheel arch and beneath the headlamp. During the diagnostic stage, we had already opened the protective sleeve, providing safe access to the damaged area without disturbing surrounding circuits or components.
Preparing and Repairing the Wiring
Following Audi’s official wiring repair standards, the process was carried out methodically and with precision:
- The corroded wire was cut back to clean copper on both sides of the break.
- A replacement section of wire was installed.
- Connectors were sealed and crimped to prevent future moisture ingress.
- A continuity test confirmed a stable connection through the repaired section.
Testing the Repair
After completing the repair, the oscilloscope was reconnected to verify communication. This time, the LIN signal appeared strong and stable, confirming that the G395 pressure temperature sensor was transmitting data correctly to the control module.
The fault code was cleared, and the system was re-tested. The compressor engaged immediately, producing a steady flow of cold air throughout the cabin.
With the wiring fault repaired and the system fully restored, Mr P’s Audi A6 was back to delivering the comfort and performance expected from a premium vehicle.
A Great Result for Our Valued Customer
For Mr P, the outcome was exactly what he needed. His Audi A6’s air conditioning was once again delivering cool air throughout the cabin. What started as a suspected re-gas turned out to be a much more complex electrical fault, but our experienced team at Smith’s of London in Croydon identified and repaired it with accuracy and care.
Every step of the process — from tracing the fault to confirming the restored signal — was completed using genuine Audi data and approved repair procedures. This ensured the repair met the same standards expected by the manufacturer.
For our technicians, this Audi A6 air conditioning repair was another example of how a detailed, methodical approach produces dependable results. Mr P drove away confident that his system was fully restored, keeping him cool and comfortable on every journey.
Smith’s of London – Croydon’s Local Specialists for Audi A6 Air Conditioning Repair
At Smith’s of London in Croydon, we combine technical expertise with genuine care for our customers. This Audi A6 air conditioning repair shows how our team uses precise diagnostics, manufacturer data, and professional repair standards to deliver results you can trust.
Every repair is carried out methodically — from identifying the root cause to confirming the system’s restored performance. Our technicians use the correct Audi wiring information, diagnostic tools, and repair procedures to ensure every job meets the highest standards of reliability.
Here’s what you can expect when you choose Smith’s of London:
- Skilled technicians specialising in Audi systems
- Honest communication and transparent advice
- Advanced diagnostic tools and approved repair methods
- Competitive pricing
- 12-month parts and labour guarantee
We’re proud to serve drivers across Croydon, Beckenham, and Coulsdon, with a {{average-rating}} star Google rating from {{review-count}} satisfied customers who trust us for reliable, high-quality repairs.
If your Audi A6 air conditioning isn’t cooling properly, call Smith’s of London on 020 8674 3377 — our skilled team will identify the issue, repair it accurately, and restore your comfort and confidence on the road.
