Audi SQ5 AC Complete Failure: Troubleshooting Guide

Had a similar issue with my 2012 Audi S5, took me a while to get it properly diagnosed. Have some experience with AC maintenance after dealing with this problem. The symptoms match exactly what I encountered, intermittent AC operation and no cold air. After thorough AC diagnostics, the workshop found defective valves in the air conditioning system. The pressure switch readings were normal, but the valves weren't regulating the refrigerant flow properly. The repair involved: Complete inspection of the cooling system, Replacement of faulty expansion valves, Recharge of the AC system, Testing under various conditions Total cost came to 1000 Euro for parts and labor. Since the fix, the AC has been working flawlessly. Which engine variant does your SQ5 have? Also, when did you first notice these symptoms, and does the blower motor run when you turn on the AC? These details would help determine if you are facing the same issue. Worth getting it checked soon, as running with faulty valves can cause additional damage to other AC components over time.

Thanks for sharing your experience. Just got my SQ5 serviced last month at 87572 KM, and these AC issues started showing up shortly after. The blower motor does run intermittently, which suggests the temperature control system might have deeper issues than just low refrigerant. Your valve diagnosis is particularly interesting since AC efficiency has been declining gradually over the past few weeks. I have the 3.0 TFSI engine and noticed that the AC noise level changes when it occasionally kicks in. Will take it to get proper AC diagnostics done this week rather than risk damaging other components. Would you recall if there were any warning signs before your valves failed completely? Mine sometimes works for a few minutes before cutting out again.

Thanks for those additional details. Yes, your symptoms sound nearly identical to what I experienced with my S5, especially the intermittent operation and varying AC noise levels. Before my valves failed completely, I noticed these warning signs: The cooling would work for 5-10 minutes then stop, Inconsistent temperature control despite the same settings, Unusual AC noise that fluctuated between loud and quiet operation, The system would sometimes work better in the morning than later in the day The AC relay would trigger, but the cooling system wasnt maintaining proper pressure due to the failing valves. These components tend to deteriorate gradually, which explains your declining performance over weeks rather than a sudden failure. Since you mentioned having recent service work, its worth checking if any AC components were disturbed during that maintenance. In my case, the expansion valve failure was unrelated to previous service work, but its good to rule out any connection. The repair cost might be similar to what I paid (1000 Euro), but catching it early could prevent additional wear on the compressor and other components.

Thanks for the detailed response. Yes, my situation sounds remarkably similar to yours down to the morning vs afternoon performance difference. My AC noise changes match exactly what you described. The blower motor runs but the cooling seems totally unusual. Given how the AC efficiency keeps dropping and the similar symptoms, I suspect you are right about the valve issue. Just booked an appointment for next week. Figured 1000 Euro is better than risking major AC system damage, especially with the compressor being much more expensive to replace. The gradual decline in performance certainly points to failing valves rather than a simple refrigerant leak or AC relay problem. Quick follow up, did you notice if restarting the car would sometimes temporarily fix the cooling when it cut out? Mine occasionally works again after a restart, but only for a few minutes. This seems to match your experience with the intermittent operation before the full repair.