Audi S3 AC Failure: Compressor Warning Signs & Fixes

I had very similar automotive cooling problems with my 2021 Audi RS3. Having some experience with AC repairs, I first thought it was the compressor too, but it turned out to be the AC control unit that was defective. The auto AC repair involved replacing the entire control module. The workshop diagnosed it using their specialized diagnostic tools, they found multiple error codes pointing to the control unit rather than mechanical components. The repair took about 4 hours total and cost me 980 Euro, including parts and labor. The symptom pattern sounds very similar to what you describe, sudden complete failure, warning lights, and stored error codes. However, before jumping to conclusions, could you share: 1. When was the last time you had the auto refrigerant levels checked? 2. Do you hear any unusual sounds when trying to activate the AC? 3. Can you still control the fan speeds, or is the entire climate control system unresponsive? 4. Have you noticed any other electrical issues recently? This information would help determine if you are dealing with the same air conditioning repair issue I experienced. Getting a proper diagnosis is crucial since AC compressor repairs typically cost significantly more than control unit replacements.

Last service was at 5000KM and everything was perfect back then including the auto refrigerant levels. Currently at 6756KM, no unusual sounds when activating. The fan speeds still work fine but there is no cooling at all. The car AC unit just wont engage the compressor. No electrical issues anywhere else in the vehicle. I see this is a known automotive cooling issue now that you mention the control module. I will check with the workshop if they can scan for these specific AC unit issues first before replacing any mechanical parts. Thanks for pointing out the control unit possibility, sounds much better than having to deal with a full compressor replacement.

Thanks for the additional details. Your symptoms match my experience almost exactly, especially the working fan speeds but no compressor engagement. This strongly indicates the same vehicle HVAC control module failure I encountered. Since your car air conditioning worked fine at the last service and failed suddenly without warning signs like noises or refrigerant leaks, this reinforces my belief that its electrical rather than mechanical. In my case, the workshop first performed a pressure test to rule out any refrigerant leak issues before focusing on the control module. The new unit resolved all problems immediately, compressor engaged normally and cooling restored. One thing to note, make sure they check the compressor electrically before replacing the control module. In rare cases, the compressor electrical connection can fail while the mechanical parts remain fine. This is a much cheaper fix than either a control module or full AC compressor replacement. Request detailed diagnostic results focusing on the control circuit. When you mentioned no other electrical issues, this matches the isolated nature of the failure I experienced with the control module. For reference, current repair costs run: Control module replacement: 800-1100 Euro, Full compressor replacement: 1800-2400 Euro, Electrical connection repair: 200-400 Euro

Thanks for the thorough explanation of your similar issue. Based on our mileage and identical symptoms, I feel much more confident about the likely cause now. Getting professional diagnostics done specifically on the car air conditioning control module seems like the smart first step, especially since the cooling system was working perfectly at my recent service. The possibility of it being an electrical rather than mechanical AC compressor issue is encouraging from a cost perspective. I will have the workshop run a complete check on the vehicle HVAC system, focusing first on the control module and electrical connections before looking at any mechanical components. The repair cost ranges you provided are really helpful for budgeting what to expect. Will book it in this week and make sure they do the pressure test first to rule out refrigerant problems. Really appreciate you sharing your experience, it potentially saved me from unnecessarily replacing the whole compressor.