VW T5 AC Failure: Compressor Issues Decoded

Having faced a similar issue with my VW T6 from 2017, I can share some experience from dealing with vehicle HVAC problems. Based on your description, this sounds exactly like what I encountered last summer. Initially thought it was the refrigerant compressor too, but after diagnostic testing, the workshop found the car air conditioning control unit was completely defective. The symptoms were identical, no cooling, warning lights, stored error codes, and complete AC system shutdown. The repair involved: Complete diagnostic scan, Removing the dashboard to access the AC control module, Replacing the control unit, System reprogramming, Testing the auto refrigerant system Total cost was 980€ including parts and labor. The repair took about 4 hours. To provide more specific advice about your situation, could you share: Have you noticed any unusual sounds when trying to activate the AC? What error codes are stored? Did the problem start suddenly or gradually? Has the system been serviced recently? These details would help determine if your issue is identical to what I experienced or if it might be something else in the air conditioning system.

Last service was done at 132533km. I want to thank you for such detailed feedback about the AC repair. After reading your post, I checked my AC compressor while running the engine, and there is indeed a slight knocking sound when engaging the clutch. The error codes show P0645 and P0647. The issue definitely came on gradually over the last few weeks, starting with reduced cooling performance before failing completely. I havent had the vehicle HVAC system serviced since buying the car. Given the symptoms and fault codes pointing to the AC compressor circuit, Im now more confident about whats wrong. Will get it checked by a workshop to confirm if its just the compressor clutch or if the entire unit needs replacement.

Thanks for the additional details. Those error codes (P0645/P0647) actually point to an electrical issue with the AC compressor clutch circuit, which is different from my initial control module problem. Combined with the knocking sound, you are likely dealing with a failing compressor clutch rather than the complete unit. On my van, the control module failure happened suddenly without warning. Your gradual cooling loss and clutch noise is a classic sign of compressor wear. This kind of auto AC repair tends to be more straightforward than my situation. The repair should involve: Compressor clutch replacement, Refrigerant leak testing, System recharge, New dryer installation Estimated costs run around 600-750€ for parts and labor, notably less than my control unit replacement. Make sure the workshop checks the entire refrigerant system during repair, as low refrigerant levels from lack of service could have contributed to the clutch failure. Based on the mileage and service history, getting a complete air conditioning service done alongside the repair would be wise to prevent future issues.

Thanks for the input. Those error codes and symptoms you mentioned match what Im experiencing exactly. Ill definitely take it to the workshop this week and have them check both the compressor clutch and the refrigerant levels. The gradual cooling loss does make more sense now knowing its likely the clutch circuit. From what you shared about repair costs, budgeting around 750€ seems reasonable. Will make sure to request a full vehicle HVAC system inspection while its being worked on. Good call on checking for refrigerant leaks too, the long service interval probably didnt help. Once the car air conditioning is fixed, Ill set up regular maintenance to avoid similar issues. Really helpful to know what to expect and discuss with the workshop. Will update once I get the final diagnosis and repair completed.