RS7 AC System Complete Failure: Common Issues and Fixes

Recently dealt with a similar AC efficiency problem on a 2014 RS6, having some experience with these kinds of issues. The symptoms were identical, complete AC failure with no response from the unit. Initially thought it was the AC relay or pressure switch, but after professional diagnosis, the root cause was defective valves in the air conditioning system. The temperature control system was completely unresponsive due to these faulty components. The repair cost came to 1000 Euro, covering both parts and labor. The workshop needed about 6 hours to complete the job, which included: Full system diagnosis, Refrigerant recovery, Valve replacement, System refill and pressure testing, Final temperature control verification Before moving forward with repairs, could you share: Any warning signs before complete failure? Current mileage? Any unusual AC noise before the system stopped working? Have you had any previous AC repairs? This information would help determine if your issue is similar and could save diagnostic time at the shop.

Thanks for the detailed response. My RS7 is at 125169 KM with the last service done 2 months ago. Before the AC stopped working completely, I noticed it was getting less cold over about a week. No unusual noises, but there was a slight chemical smell from the vents. The AC diagnostics you mentioned make sense as a starting point. Wondering if my symptoms point more toward a refrigerant leak rather than valve issues, given the gradual loss of cooling. Would definitely help to know if pressure testing revealed any specific points where the system commonly fails on these models. Planning to get it checked this week, as summer is approaching and a properly working AC system is essential.

Based on those additional symptoms, especially the gradual cooling loss and chemical smell, this does point more toward a refrigerant leak than the valve issues I encountered. The AC efficiency typically degrades slowly with a leak, while valve failures tend to cause more sudden problems like we had in our case. After dealing with multiple AC system issues in my RS6, I learned these common leak points: Condenser connections, AC lines and fittings, Evaporator core, Compressor shaft seal The chemical smell you mentioned is particularly telling. When refrigerant leaks past certain seals, it often carries trace amounts of compressor oil, creating that distinct odor. My AC temperature control stayed functional even with low refrigerant, unlike the complete failure from bad valves. A proper pressure test should quickly identify the leak location. Getting this addressed promptly is smart, running the AC system with low refrigerant can damage the compressor, turning a simple leak repair into a much costlier fix. Based on the mileage, it could also be time to service the AC relay and other cooling system components as preventive maintenance. Keep us posted on what the diagnostic reveals. Would be useful to know the actual failure point to help others with similar AC noise or cooling problems.

Thanks for the input. The chemical smell combined with gradual cooling loss does make refrigerant leak seem more likely than valve failure. Will definitely have them do a thorough AC diagnostics with pressure testing to pinpoint the exact leak location. The information about the compressor oil causing that smell makes sense. My main concern is avoiding major compressor damage, so I will get it checked right away rather than risk a more expensive repair. Since the car has decent mileage, having them do a full AC maintenance inspection while they are at it seems sensible. I will update once the blower motor and full system have been tested and the actual issue is found. Hopefully it is just a simple leak that can be fixed without replacing major components. Having a properly working AC system is critical, so getting this resolved before summer is a priority.