VW Golf TDI AC Dead, Compressor Won't Engage

I had a very similar issue with my 2006 VW Jetta TDI. As someone with moderate experience working on cars, I initially thought it was just a refrigerant leak causing the A/C system problems. The symptoms matched exactly what you describe, no compressor engagement and complete lack of cold air. My workshop ran a full diagnostic and found that undervoltage in the vehicle was preventing the A/C compressor from engaging properly. The pressure switch was receiving insufficient power to trigger the compressor. The repair involved: Testing the electrical system, Replacing faulty voltage regulator, Checking A/C system pressure, Verifying compressor operation Total cost was 240€ and the HVAC system has worked flawlessly since the fix. Before suggesting more specific solutions, could you share: Are you getting any specific error codes? Have you noticed any other electrical issues like dim lights? Did the problem start suddenly or develop gradually? Have you checked the fuses related to the A/C system? This information would help determine if your issue matches what I experienced or if its potentially something else causing the compressor to not engage.

Thanks for sharing your experience. At my latest 85000km service everything was working fine. The AC relay was actually the first component my mechanic tested since its a common failure point for these symptoms. After checking both the pressure sensor and running diagnostics, we found the electrical connectors to the compressor had significant corrosion buildup, preventing proper contact. A thorough cleaning of the connections and replacing one damaged terminal restored full function to the HVAC system. The total repair only came to 90€ since no major parts needed replacement. The belt tensioner was also inspected while accessing the compressor area but was still in good condition. Has your air conditioning system been working reliably since the voltage regulator replacement?

Good to hear you got the issue resolved at a reasonable cost. The voltage regulator fix on my Jetta has kept the A/C system running perfectly for over 2 years now without any problems. Your corrosion issue is actually quite common with these VW models. The AC relay and pressure switch connections are particularly susceptible to moisture damage in the engine bay. Its worth checking these points during regular maintenance to prevent similar failures. Since the fix, I make it a habit to inspect the electrical connectors around the A/C system components during oil changes. A quick spray of electrical contact cleaner on the connections has helped prevent any repeat issues with the pressure sensor or compressor wiring. The 90€ repair cost shows the value of proper diagnosis, much better than unnecessarily replacing the compressor or other major components. Glad your belt tensioner checked out ok too, as thats another common wear point that can affect A/C performance.

Thanks for the detailed info about the Jetta fix. The problem with my Golf actually started quite suddenly about 2 weeks after the 85000km service. Everything was working fine before that. After checking both the pressure sensor and running diagnostics, we found the electrical connectors to the compressor had significant corrosion buildup, preventing proper contact. A thorough cleaning of the connections and replacing one damaged terminal restored full function to the HVAC system. The total repair only came to 90€ since no major parts needed replacement. The belt tensioner was also inspected while accessing the compressor area but was still in good condition. The A/C system has been working perfectly since the repair. The mechanic recommended spraying contact cleaner on the electrical connections during future services to prevent similar issues. Maintaining proper connections seems crucial for these components to function correctly. Based on both our experiences, it seems electrical issues are common causes of A/C system failures in these cars rather than mechanical problems with the compressor itself. Have you had any other HVAC related issues since your voltage regulator repair?