RS7 HVAC System Complete Failure, Common Control Issues

As someone with moderate repair experience, I dealt with a similar issue on my 2020 RS6. The symptoms were nearly identical, unresponsive control panel and HVAC system failures. The root cause was a faulty wiring harness connection affecting the temperature sensor and blower motor signals. Electronic faults like these can be tricky to diagnose without proper diagnostic equipment. After several attempts to fix it myself, I had a workshop trace the issue to corroded connectors in the main HVAC control module. The repair involved cleaning the connections and replacing one damaged plug, costing 95 Euro in total. The whole job took about 2 hours, and the system has worked flawlessly since then. What engine variant does your RS7 have? Also, are there any specific error codes showing up? This information would help determine if your issue matches what I experienced. The RS models from this generation share many components, but there are subtle differences between model years and variants that could affect the diagnosis. Would also be good to know if the issues started gradually or suddenly, as this can indicate whether its a wiring problem or a more serious control unit failure.

I have the same issues appearing after my last service at 91943KM. The climate control system keeps failing intermittently. The air conditioning works occasionally but cuts out frequently. The electrical connectors seem to be the likely culprit since the temperature sensor readings are erratic on the display. My 4.0L TFSI engine has been otherwise reliable, but these HVAC gremlins are quite frustrating. Thanks for sharing your experience, sounds very similar to what I am dealing with. The error codes mentioned are identical, suggesting the wiring harness might indeed be the root cause.

Good to hear back about your RS7. After you mentioned the erratic temperature sensor readings, I am even more convinced we had the same issue. In my case, the intermittent failures also started showing up right after a service appointment, around the 85000km mark. The key indicator was exactly what you described, those fluctuating temperature readings on the display. When the air conditioning system started cutting out on my car, the control panel would sometimes show wildly inaccurate temperatures, which pointed directly to compromised electrical connectors in the wiring harness. Since your 4.0L TFSI has the same general HVAC layout as mine, the repair approach should be similar. The workshop will need to inspect the main harness connection points, particularly where they connect to the blower motor and temperature sensor assembly. Based on my experience, you might want to have them specifically check the connector block behind the control panel. In my case, there was visible corrosion there that was causing the intermittent connection issues. Have you noticed if the problems get worse when the car hits certain bumps or during specific weather conditions? This information could help pinpoint exactly where in the wiring harness the issue lies.

Thanks for the detailed follow-up. Yes, the problems definitely get worse during wet weather and over speed bumps, exactly as you described. The temperature sensor readings go completely haywire when hitting larger bumps, sometimes showing -40 degrees then jumping to +50 within seconds. The climate control system then shuts down completely. I will mention the wiring harness and electrical connectors when booking the service appointment. With my car showing the same symptoms after maintenance, and the error codes matching your experience, it seems replacing the corroded connectors might solve the issue. The 95 Euro repair cost you mentioned is much more reasonable than I feared. One last question, did your workshop mention any preventive measures to avoid future corrosion issues with the HVAC system components? I want to make sure this doesnt become a recurring problem, especially given how the electronic faults seem to appear after routine servicing.