SQ8 AC Failure: Compressor vs. Refrigerant Leak Alert

Having some experience working on Audi cars, I encountered a similar AC unit issue with my 2021 Q8. The symptoms matched yours, no cooling and warning lights, though mine started with intermittent cooling before failing completely. The air conditioning repair involved replacing the AC control unit, which was causing the compressor to not engage properly. Initially, the workshop suspected a refrigerant leak or AC compressor failure, but diagnostic tests revealed the control module was the culprit. The repair took about 6 hours and cost me 980 Euro, including parts and labor. A few questions to help diagnose your specific case: Did you notice any unusual noises from the AC compressor area before the failure? Does the blower motor still work, just without cold air? Have you had any recent AC service or refrigerant recharge? Are there any other warning lights besides the AC warning? Without proper diagnosis, its hard to determine if your issue is identical, but the symptoms align closely with what I experienced. The workshop should perform a full AC system pressure test and electrical diagnosis before replacing any components. Let me know these details about your vehicle and I can share more specific information about the repair process.

Thanks for the helpful response. My SQ8 has only 27058 KM and got its last service 2 months ago. The automotive cooling issue started suddenly without warning. To answer your questions, no strange noises before the failure, the blower works fine but produces warm air, no recent AC service since the scheduled maintenance, and only the AC warning light is showing. I checked under the hood for obvious refrigerant leaks around the cooling system connections but found nothing visible. The AC unit issues seemed to come out of nowhere, which makes me think the control module diagnosis makes sense. Will have the workshop do a full system check to be certain.

Thanks for those details about your SQ8. The symptoms sound nearly identical to what I experienced with my Q8, especially the sudden failure without warning signs. The fact that your blower works but only produces warm air strongly suggests either a control module issue or AC compressor failure. Since your vehicle got serviced recently, I would focus the diagnosis on the electrical components rather than auto refrigerant levels. When my control module failed, the system also showed no visible leaks, and the AC compressor would not engage despite having proper refrigerant pressure. The workshop should specifically check: 1. Control module functionality 2. AC compressor clutch engagement 3. System pressure readings 4. Electrical connections to the compressor The repair process for the control module replacement is relatively straightforward once diagnosed. My cooling system was back to normal within the same day. The warranty might cover this since your car is quite new with low mileage. One tip from my experience: ask the workshop to check all cooling system components while they have it open, including the condenser and expansion valve. This helps prevent future air conditioning repair needs.

Your AC unit issues really do sound identical to what happened with mine. Based on your feedback and the lack of warning signs or refrigerant leaks, I'm feeling more confident its the control module rather than a compressor failure. The fact that everything was fine during the service 2 months ago and failed suddenly backs this up. I'll schedule the workshop visit and request the complete diagnostic check you mentioned, especially focusing on the electrical components and control module. Makes sense to have them inspect all cooling system parts while they're working on it. Really hoping its covered under warranty since the car is practically new. Thanks for sharing your repair experience, its helped narrow down the likely cause and saved me from jumping to conclusions about the compressor. Will update once I get the diagnosis and repair completed.