Audi RS6 HVAC Total Failure, Compressor Issues Guide

Had the exact same issue on my 2015 Audi S6 last summer. The A/C system shutdown was caused by an undervoltage protection triggering the pressure switch, which then disabled the A/C compressor. The root cause turned out to be a failing belt tensioner that wasnt providing proper tension to the serpentine belt. This caused irregular power delivery to the A/C compressor, triggering the safety cutoff. Initial symptoms matched yours, complete HVAC system shutdown and no cooling. The pressure switch was doing its job by protecting the A/C compressor from damage due to improper belt operation. This isnt a small fix since accessing the belt tensioner requires removing several components. The repair involved: Replacing the belt tensioner assembly, Installing a new serpentine belt, Testing the A/C system pressure, Recharging the A/C system If you get it checked, ask them to inspect the belt tensioner and serpentine belt condition first before assuming its just a pressure switch issue. The tensioner failure can lead to more serious problems if left unchecked, potentially damaging other belt-driven components. The diagnostic scan should show pressure-related codes that will help pinpoint if its indeed a belt tensioner problem versus a simpler electrical issue.

This definitely rings a bell, I had a similar issue with my 2018 RS6 where the A/C compressor completely shut down. The pressure sensor was reporting errors and the entire A/C system went offline. After diagnosis, it turned out the belt tensioner was the culprit, exactly like your case. Wanted to check how much the repair ended up costing you? Also curious if youve had any recurring A/C system issues since getting it fixed? My repair was about 6 months ago and so far everything seems stable, but Im always cautious about potential refrigerant leaks developing later.

Since getting the repair done at the shop, my A/C compressor has been working perfectly with no shutoff issues. The undervoltage problem was resolved completely, costing 240 Euro for the full diagnostic and repair work. The A/C system has remained stable with proper pressure readings from the pressure sensor. No refrigerant leaks have developed and the belt tensioner is maintaining correct tension. The repair shop did a thorough job testing the system pressure after fixing the undervoltage issue. Its good to hear your repair has been holding up for 6 months. The pressure switch and belt tensioner fixes tend to be long-lasting solutions when done properly. Just keep an eye on your temperature performance as refrigerant leaks would show up first as gradually reduced cooling.

Just wanted to share my experience after visiting the mechanic for my RS6 air conditioning issue. The diagnostic confirmed the belt tensioner problem and they found slight wear on the serpentine belt too. The total repair came to 480 Euro, which included: New belt tensioner assembly, Fresh serpentine belt, Labor costs, System pressure test, Refrigerant top-up The mechanic I found was thorough and explained how the failing tensioner was causing the pressure switch to trigger the HVAC system shutdown. The repair took about 4 hours since they had to remove several components to access the belt area. After 6 months, the air conditioning is working perfectly with no pressure switch errors or compressor issues. The cooling performance has remained consistent and I have not noticed any refrigerant leaks. Money well spent considering the potential damage a failed belt could have caused to other components.