VW Caddy A/C Dead: Common Sensor Failure Alert

I had a similar issue with my 2009 VW Golf, the A/C system completely stopped working and the compressor wouldnt engage. As someone with some basic car maintenance experience, I first thought it was a refrigerant leak. Took it to my regular workshop where they diagnosed an undervoltage problem affecting the A/C compressor engagement. The pressure sensor was giving false readings due to insufficient power supply. The complete diagnosis and repair, including replacement of the faulty components in the HVAC system, cost me 240€. The workshop explained that low voltage can trigger the A/C system safety features, preventing compressor engagement to avoid damage. This seems common in VW models from that era. To better assist with your specific case, could you share: Does the issue occur constantly or intermittently? Have you noticed any other electrical issues? When was the last time the A/C system was serviced? What error code is stored? These details would help determine if youre facing the same underlying electrical problem or if its a different A/C component failure.

Thanks for sharing your experience. Mine also started intermittently before failing completely. Last service was at 58000km where they checked the AC system but found no issues. The error code shows P0645 which points to the AC relay circuit. The compressor shows no signs of mechanical damage and the belt tensioner appears to be in good condition. Given your solution, I will have them check the voltage at the AC relay and pressure sensor first before replacing any major components. Did your repair also include checking or replacing the AC relay? Hoping my fix will be similarly straightforward and not require a full A/C compressor replacement.

Can confirm the AC relay was actually part of my repair. The workshop found that the relay switch was causing intermittent voltage drops, which then affected the pressure sensor readings. They replaced both components as part of the repair since they often work together in the system. Your P0645 code definitely suggests a relay circuit issue similar to what I experienced. The good news is that the belt tensioner and compressor being in good shape likely means you wont need major mechanical repairs. In my case, the refrigerant level was also correct, ruling out a refrigerant leak. After fixing the relay and sensor, my AC system has worked flawlessly for over 50,000km now. The electrical fix was much more cost-effective than replacing the compressor would have been. Worth noting that on these VW models, the AC relay is relatively accessible and replacement is straightforward compared to other potential AC repairs. Make sure they also test the power supply to the entire AC system while diagnosing, as this can reveal other potential voltage issues.

Thanks for the clarification about the relay being part of your fix. This matches perfectly with my P0645 error code. I will definitely have the shop focus on checking both the relay and voltage issues in the HVAC system. After researching more, I found several similar cases where the pressure sensor and relay problems were linked on these VW models. The intermittent nature of my issue before complete failure seems to match the typical pattern of relay deterioration. I will schedule an appointment next week and specifically request voltage testing across the A/C system components, especially the pressure switch circuit. Based on your experience, I feel more confident now that this might be resolved without major expense or compressor replacement. One final question, did you notice any improvement in overall A/C performance after the relay and sensor replacement compared to before the issues started? Mine had been slightly weak even before failing completely.