Audi S1 AC System Complete Failure, Common Fixes

As someone with moderate car repair experience, I faced an identical issue with my 2014 Audi S3. The symptoms were exactly the same, complete AC failure with no response from the cooling system. After initial diagnosis, my mechanic found defective valves in the air conditioning system, which prevented proper refrigerant flow. The pressure switch was also not engaging properly, causing the AC relay to stay inactive. This explained why the blower motor wasnt responding at all. The repair involved: Complete inspection of the AC efficiency, Replacement of faulty control valves, Testing the cooling system pressure, Recharging the refrigerant Total cost came to 1000 Euro, including parts and labor. The repair restored full functionality, and the AC has worked flawlessly since then. Before suggesting more specific solutions, could you provide: Current mileage on your S1, Any warning lights on the dashboard, Any unusual noises before the system failed, Last AC service date, Whether the problem occurred suddenly or gradually This information would help determine if youre dealing with the same underlying issue.

Latest service was done at 85000 KM, currently at 87413 KM. I noticed the problem came on gradually over about two weeks. No warning lights on the dash and no strange noises before the complete failure. The blower motor worked fine for cabin air until last week. Really appreciate the detailed info about the valves, sounds very similar to what I am experiencing with the temperature control system. Going to schedule a pressure test to check for a refrigerant leak first since that seems like a logical starting point.

Thanks for providing those details. Based on what you described, your S1s symptoms do match closely with what I experienced, especially the gradual failure pattern and blower motor behavior. In my case, the pressure test revealed the control valves had deteriorated over time, causing a slow refrigerant leak. The AC diagnostics showed the pressure switch wasnt receiving proper signals, which eventually led to the complete system shutdown. Since your mileage and timeline match closely with when my issues started, Id strongly suggest having the AC relay and control valves checked along with the pressure test. The gradual failure often indicates a progressive issue rather than a sudden component failure. A full AC system pressure test should cost around 150 Euro. If the diagnosis confirms valve issues like in my case, you might want to consider replacing both valves together since they tend to wear at similar rates. This preventive approach saved me from potential future repairs. The temperature control system issues typically stem from these valve problems, as the system cant regulate pressure properly when theyre failing. Would definitely get this checked before the weather gets warmer.

The AC pressure test sounds like a good starting point. Interesting that you mentioned similar valve deterioration issues, that matches the gradual decline I experienced. The timing between my last service and when problems started does seem to point toward a wear-related failure rather than sudden damage. Given the mileage and age of my S1, investing in both valve replacements makes sense if the cooling system inspection reveals similar issues. Better to fix everything while the system is already opened up. 150 Euro for diagnostics is reasonable considering the complexity of modern AC systems. Will book the pressure test this week and ask them to specifically check the AC relay and control valves during the inspection. Really helpful to know what specific parts to have them look at, especially since the temperature control stopped responding in the same way you described. Will update once I get the results from the refrigerant leak detection test and full AC diagnostics.