Cadillac SRX AC Compressor Failure and DIY Solutions

Had nearly the same issue with my 2006 Cadillac CTS last summer. Have some experience working on basic car maintenance but needed professional help with this one. The HVAC system symptoms were identical, no engagement and complete lack of cooling. Initially thought it was the compressor too, but it turned out the main culprit was an undervoltage issue affecting the AC relay and pressure sensor. Took it to a workshop where they diagnosed a faulty voltage regulator that was causing electrical system fluctuations. This was preventing proper communication between the AC components. Total repair cost was 240€ including parts and labor. They also performed a full inspection of the A/C system to check for any refrigerant leaks while they were at it. Before suggesting more specific solutions, could you share: Have you noticed any other electrical issues like dimming lights or slow starter? What error codes exactly did you get? Does the AC fan still work when you turn on the system? Have you had any recent battery or alternator issues? This info would help determine if your issue matches what I experienced or if you might be dealing with a different problem.

Just had my periodic service at 187415 KM where they did a full A/C system inspection. After checking pressure switch readings and running diagnostics, they found a refrigerant leak in one of the lines near the compressor. The error codes in my case were P0645 and P0533. The techs found that while the compressor itself was fine, the system had lost pressure due to the leak, triggering the safety cutoff. Worth checking if you have similar line damage before replacing major components. The pressure readings were way below spec, which explains why the compressor wouldnt engage. My repair involved fixing the line and recharging the system, much cheaper than a full compressor replacement. Worth having a proper leak test done first.

Thanks for sharing those error codes, P0645 and P0533 often point to AC pressure sensor and A/C compressor circuit issues. In my CTS, I initially had similar readings but noticed that the pressure switch itself wasnt receiving proper voltage input. After having my voltage regulator replaced, they found some hidden refrigerant leaks during the pressure test. The lines near the A/C compressor are a common failure point. My repair costs were actually pretty similar, fixing the leak and recharging the system ran about 250€. The pressure readings on mine were also triggering the safety cutoff, preventing compressor engagement. One thing to watch for, make sure they do a UV dye test after the repair to confirm all leaks are fixed. When my system was recharged, they discovered a second small leak that might have caused problems later. From your description, sounds like you had the same underlying issue. Good call getting that full inspection done, catching those line leaks early prevents more expensive A/C compressor damage down the road.

Thanks everyone for the helpful replies. After getting everything fixed up, I wanted to close the loop on what solved my AC issues. The root cause was exactly what the responses suggested, a refrigerant leak near the A/C compressor that triggered the safety shutoff. Final repair breakdown: Leak detection and pressure testing: 85€, Line repair and new fittings: 160€, System recharge with refrigerant: 95€, UV dye test to verify fix: 45€ Total came to 385€, which beats replacing the whole compressor. The AC relay and pressure sensors all tested fine once proper system pressure was restored. Key learning: always check for leaks before assuming major component failure in the HVAC system. For anyone searching later with similar symptoms, those P0645 and P0533 codes pointed to the pressure loss, not a bad compressor. The belt tensioner and other mechanical parts were all in good shape. System is now cooling perfectly after the fix.