T-Roc HVAC Failure Linked to Temperature Sensor Issues

Had a similar issue with my 2018 VW Tiguan last summer, and being somewhat experienced with VW maintenance, I recognized those symptoms immediately. The complete failure of the HVAC and error messages turned out to be a defective air conditioning control unit, not just a sensor issue. Initially, the workshop also suspected a temperature sensor malfunction, but after proper diagnostics, they found the control unit was the root cause. The repair included: Full diagnostic scan, Removal and replacement of the AC control unit, Sensor calibration of the new unit, System pressure test, Refrigerant recharge Total cost was 980€, which included parts and labor. The vehicle maintenance history helped identify the issue faster, as they could see no previous cooling system or sensor-related repairs. Before suggesting specific solutions, could you share: Complete error codes youre getting, Whether the coolant level is normal, If you notice any coolant leak, Whether the issue started gradually or suddenly, If the engine cooling fans are operating normally This information would help determine if youre facing the same issue I encountered or if its something different.

Thanks for the information. The issue started suddenly during my latest service at 45377km. The error codes show P0118 and P0116. Coolant level is perfect, no leaks visible, and the engine cooling fans work as expected. The temperature gauge shows normal readings when the engine is running. Feels like the sensor calibration might have gotten messed up during the maintenance work.

Based on those error codes and symptoms, your situation differs slightly from what I experienced with my Tiguan. The P0118 and P0116 codes specifically point to the engine coolant temperature sensor circuit, while my issue was with the HVAC control unit itself. Since your symptoms appeared right after service, and considering the temperature gauge shows normal readings, this strongly suggests a calibration issue or damaged wiring during the maintenance work. My control unit failure showed more erratic temperature readings. In your case, I recommend: Having the workshop check the wiring connections at the temperature sensor, Verify if any connectors were disturbed during the service, Request a sensor calibration reset This should cost significantly less than my 980€ repair, likely around 150-200€ if its just recalibration and connection check. If they find damaged wiring, costs might increase. The good news is your engine cooling system appears to function normally, and there is no coolant leak. This matches what I learned during my repair, when the coolant system itself works fine but sensors act up, its typically a simpler fix than a full control unit replacement like I needed. Would definitely push the service center to check their work since the issue started right after maintenance.

Thanks for the detailed response. You nailed it about checking the work just done during service. I called the workshop and explained everything, mentioning the error codes and the timing of the HVAC system failure. They admitted they had removed several components around the temperature sensor during the scheduled maintenance. They agreed to check their work at no cost, and it turns out their technician had damaged the wiring harness while reinstalling a clamp near the cooling system components. The vehicle maintenance report shows they fixed the wiring and recalibrated the temperature sensor. Total cost was 0€ since they covered it under their service warranty. The cooling system is now working perfectly, and all error codes are gone. The HVAC system started working normally right after they repaired the wiring. Much better outcome than having to replace the entire control unit like in your case. Really appreciate your help in identifying this as a potential service-related issue rather than a major component failure.