Audi A6 AC Compressor Failure: Diagnostic Guide Needed

Recently dealt with similar A/C system issues on my 2009 Audi A4 2.0T. The symptoms matched exactly, no compressor engagement and complete loss of cooling. After diagnosis, the AC relay had failed, preventing proper voltage supply to the A/C compressor. The fix involved replacing the faulty relay and performing a thorough A/C system check. The technician also found a minor refrigerant leak at one of the pressure switch connections, which needed addressing to prevent future issues. The complete repair included: Testing the A/C system voltage, Replacing the AC relay, Fixing the leaking pressure switch connection, Recharging the A/C system with correct refrigerant levels This was a moderate repair job. While not the most serious issue possible with an A/C system, leaving it unfixed could lead to more extensive A/C compressor damage. The entire repair took about 3 hours at the shop. When the A/C compressor fails to engage, its often electrical rather than mechanical. Getting it diagnosed early helps prevent more costly repairs down the line.

Thanks for sharing your experience. My A/C system in my Audi A6 had very similar symptoms last summer. The pressure switch was also the culprit in my case, along with a significant refrigerant leak from a cracked line. The HVAC system needed a thorough inspection before they found all the issues. Would you mind sharing what the total repair cost was in your case? Curious if you had any recurring problems since the fix? In my situation, the air conditioning has been working flawlessly after the repair, but I want to make sure I keep an eye on potential warning signs.

Great to share an update on my A/C repair situation. The relay switch replacement and voltage issue fix turned out to be exactly what my A4 needed. Total cost came to 240 Euro which included diagnosing the undervoltage problem and installing a new relay component. The HVAC system has been running perfectly since the repair. The A/C compressor engages smoothly now and the cooling performance is back to normal. Having a proper diagnosis from a qualified technician made all the difference, they correctly identified the electrical nature of the problem rather than assuming it was a major mechanical failure. No recurring issues since the fix. The belt tensioner and all other A/C system components were also checked during the service to ensure there were no additional problems developing. This preventive inspection helped confirm there were no refrigerant leaks or other potential issues to worry about. Regular maintenance checks are still important though. Having the A/C system inspected annually helps catch any developing problems before they become serious repairs.

Thanks everyone for the helpful responses. Took my car to a new mechanic last week and wanted to share how it went. The diagnosis revealed multiple issues with the HVAC system, a faulty relay switch, low refrigerant from a leak, and a worn pressure sensor. The repair cost came to 450 Euro total, which included: New relay switch installation, Fixing the refrigerant leak, Pressure sensor replacement, Full system recharge, Labor costs for diagnosis and repair The A/C compressor now engages properly and the cooling works perfectly again. The mechanic was thorough and took time to explain each issue. They also did a complete system pressure test to ensure there were no other leaks. The air conditioning has been working great for the past week. Temperature control is much more consistent than before. Definitely worth getting it fixed before summer hits full force.