Audi S8 AC Compressor Failure, Fix Guide & Costs

Had a similar AC unit issue with my 2009 Audi S6 last summer. With some experience working on HVAC systems, I initially thought it was the AC compressor too, but it turned out to be the control unit. The symptoms were identical, no response from the AC system, warning lights, and error codes. After taking it to a specialized auto AC repair workshop, they diagnosed a faulty electronic control module rather than a mechanical failure. The repair included: Complete diagnostics, Replacement of the AC control unit, System recalibration, Auto refrigerant pressure test, Full system check Total cost was 980 Euro, which covered parts and labor. The repair took about 4 hours, and the vehicle HVAC system has worked flawlessly since. Before suggesting specific solutions for your S8, could you share: Have you noticed any unusual sounds when trying to activate the AC? What are the specific error codes showing? Did the issue start suddenly or develop gradually? When was the last AC service performed? This information would help determine if your issue is similar to what I experienced or if its potentially a different component causing the problem.

Last service was 2 months ago at 84646 KM. The compressor makes a loud grinding noise when engaging, which wasnt mentioned in the initial diagnosis. The clicking sound is quite aggressive compared to normal operation. Had the refrigerant checked during service and levels were fine, so I suspect its more of a mechanical issue with the AC compressor itself rather than a control unit problem. The noise definitely points to bearing failure inside the compressor assembly. Wondering if anyone can confirm if this specific sound matches their experience before committing to the repair.

Thanks for the additional details. After hearing about the grinding noise, I need to revise my initial assessment. While my S6 AC problem was control unit related, your symptoms are quite different and point directly to automotive cooling system mechanical failure. The grinding noise when engaging is a telltale sign of AC compressor bearing failure, had this exact issue on a previous vehicle. The aggressive clicking is typically the clutch trying to engage but meeting resistance from the seized bearings. With proper refrigerant levels confirmed during recent service, this further supports mechanical failure rather than a refrigerant leak or electrical issue. The compressor is likely seizing, which if left unaddressed, could cause: Complete system failure, Belt damage, Additional strain on other components The repair on my earlier vehicle included: New compressor assembly, Receiver drier replacement, System flush, Fresh refrigerant charge Total cost was around 1400 Euro. The repair resolved all issues and restored proper car air conditioning function. Given your symptoms, particularly the grinding noise, would strongly recommend addressing this soon to prevent secondary damage to other AC components.

The grinding noise description from the previous replies definitely aligns with my AC compressor concerns. Since posting my initial question, the sound has actually gotten worse during startup attempts. Based on the feedback and similar experiences shared, I will proceed with the complete compressor replacement. The estimated 1400 Euro repair cost seems reasonable considering the comprehensive work needed for a proper automotive cooling system fix. Having confirmation about the bearing failure symptoms from others who encountered similar auto AC repair issues is really helpful. Will schedule the repair this week to include: Full compressor replacement, System flush, New refrigerant, Associated parts replacement Will post an update after the car air conditioning repair is completed to share the final diagnosis and actual repair costs for others who might face similar AC unit issues in the future.