VW Transporter A/C Failure: Compressor Warning Signs

I had a similar issue with my 2017 VW Passat last summer and can share my experience, having worked on a few basic car repairs before. The A/C system completely stopped working, showing similar symptoms. After checking with a diagnostic tool, it turned out the problem was related to undervoltage affecting the HVAC system, specifically the pressure sensor circuit. The low voltage was causing the A/C compressor to disengage as a protective measure. The workshop found that the belt tensioner was worn, causing inconsistent power delivery to the alternator. They also performed a complete check of the A/C system components and refrigerant levels to rule out any leaks. The total repair came to 240€, including parts and labor. Before suggesting specific solutions for your Transporter, it would help to know: Does the A/C compressor clutch engage at all when you turn on the system? Have you noticed any changes in electrical system behavior (dimming lights, slow starter)? What specific error code is showing up? Any unusual noises from the engine bay when the A/C is switched on? These details would help determine if your issue is similar to what I experienced or if its something else in the A/C system.

Just had my last service at 96500km and faced this exact problem. The A/C compressor clutch wasnt engaging at all. A full diagnostic revealed a refrigerant leak from a corroded connection near the evaporator. The relay switch was also faulty, preventing proper engagement of the A/C system. The repair involved replacing the leaking connection, a system evacuation, and installing a new relay. The shop also recharged the A/C system with fresh refrigerant after fixing all leaks. Total cost was 380€. Consider having a professional pressure test done, its crucial for pinpointing exact leak locations in the A/C system. The symptoms you describe match what I experienced, especially the compressor not engaging.

Thanks for sharing your repair experience. I encountered nearly identical issues with my VW Transporter when the AC system failed. After your post, I double-checked my repair invoice, my AC relay switch was also replaced along with fixing a slow refrigerant leak. The pressure sensor readings were erratic before the repair, causing the compressor clutch to disengage out of nowhere. The HVAC system would sometimes work for a few minutes before cutting out completely. The root cause in my case was also a corroded connection, but mine was near the condenser rather than the evaporator. The repair shop did a full vacuum test of the system after replacing the AC relay and fixing the leak point. Total cost in my case was closer to 420€ since they also had to replace one pressure switch that had failed due to moisture intrusion. If anyone else faces similar symptoms, getting a proper pressure test done is essential, it helped identify the exact location of the leak without replacing parts unnecessarily. The relay switch and pressure sensor circuit should also be tested since they are common failure points that prevent proper compressor engagement.

Thanks everyone for the helpful information. Wanted to follow up and share what the actual problem turned out to be with my VW Transporter A/C. After taking it to the shop, they found multiple issues affecting the A/C system. The pressure sensor was giving false readings due to a faulty relay switch that was causing intermittent power problems. They also discovered a small refrigerant leak at a connection point. The repair involved: Replacing the defective relay switch, Installing a new pressure sensor, Fixing the leaking connection, Full system evacuation and recharge Total cost came to 460€ including parts, labor and refrigerant. The A/C is now working perfectly again with good cooling performance. The diagnostic fee was worth it since they found all the underlying issues rather than just replacing parts out of nowhere. For others with similar symptoms, definitely get the pressure sensor and relay switch checked along with a proper leak test of the A/C system. These components often fail together and cause the compressor to disengage.