Dead Jeep Commander A/C, Compressor Won't Engage

Had a similar issue with my 2009 Jeep Grand Cherokee 3.6L. The air conditioning system showed identical symptoms, no engagement and complete failure to start up. The root cause was actually not the A/C compressor itself, but a failed relay switch in the HVAC system. When the relay switch fails, it prevents the proper voltage from reaching the A/C compressor, causing it to not engage at all. This undervoltage condition triggers the error code. The diagnosis process revealed the pressure switch was also faulty, which is a common issue in these models. Both components work together, the pressure switch monitors refrigerant pressure while the relay controls power to the compressor. This was not a major repair compared to a full compressor replacement. The fix involved replacing both the relay and pressure switch to restore proper functionality to the air conditioning system. Getting this diagnosed correctly saved significant repair costs versus unnecessarily replacing the entire compressor. Worth having a qualified technician check these components first before assuming the worst case scenario with the compressor itself. The symptoms often mimic a failed compressor but can be caused by these smaller electrical components.

Thanks for sharing that, it sounds exactly like what I was dealing with! The AC relay and pressure switch diagnosis makes perfect sense since my belt tensioner looked fine but the A/C compressor still wasnt engaging. Would you mind sharing roughly what you paid for the repair? Also curious if youve had any other HVAC system issues since getting it fixed? Want to make sure I have a good reference point before heading to the shop.

After taking it to my mechanic, the A/C compressor issue was completely resolved by fixing the undervoltage problem. The total repair cost came to 240 Euro, which included diagnosing and replacing the faulty relay switch. The air conditioning has been working perfectly since the repair, no refrigerant leaks or pressure sensor problems. The A/C compressor now engages smoothly every time without any error codes. Looking back, Im glad I didnt jump to replacing the entire compressor, as the real issue was much simpler and less expensive to fix. When the pressure switch and relay work together properly, the system maintains correct voltage to the compressor. This repair was done 8 months ago and the HVAC system has performed flawlessly since then with no additional issues.

Just got back from the mechanic and wanted to share my experience. You were right, the pressure sensor and relay were the culprits. Total cost was 275 Euro for parts and labor, which felt fair considering what I was worried about initially. The mechanic showed me the old pressure switch which was completely corroded. Once they replaced both components and checked the belt tensioner, my air conditioning started working perfectly again. The compressor now engages immediately when I turn on the system. Really grateful for the heads up about checking these smaller parts first. Saved me from potentially getting sold an unnecessary compressor replacement that could have cost over 1000 Euro. No more error codes and the system is cooling better than it has in months. Running solid for the past 2 weeks now. Looks like this was the right fix for the issue. Think Ill stick with this mechanic, they were honest about the actual problem instead of trying to upsell me on bigger repairs.