VW T5 Climate Control Nightmare: Multiple System Failures

I had a similar issue with a VW T6 2011, and can share my experience as someone with moderate expertise in car electronics. The climate control malfunction and dashboard warnings were caused by a damaged wire connection to the humidity sensor. The windshield fogging detection system was also affected, causing several systems to fail simultaneously. My workshop ran a full diagnostic scan which pointed to the humidity sensor circuit. They found corroded connector pins where the humidity sensor wiring meets the main harness. The fix involved cleaning the connections and replacing a short section of wiring plus the connector itself. Total cost was 95€ for parts and labor. The symptoms disappeared completely after repair, climate control working properly, no more error codes, and all auxiliary systems like mirror heating back to normal. To help diagnose your specific case, could you share: What exact error codes are you getting? Does the malfunction happen more frequently in wet weather? Are there any other electrical issues beyond the climate system? Have you noticed any water ingress around the windshield area? This information would help determine if your T5 has the same root cause as my T6 did.

Just had my 27000km service last week and noticed similar sensor calibration issues. The workshop explained that the humidity sensor malfunction can affect multiple systems at once. For me, the electrical issue started showing right after a period of heavy rain. After checking with Autocom diagnostic, my fault codes pointed to the same area. The car sensor cluster near the rearview mirror was affected by moisture damage, impacting visibility systems and causing dashboard warning lights. Rather than replacing the entire unit, the tech cleaned and resealed the connections first. This fixed about 80% of the problems, but I still notice occasional glitches with the mirror heating. Planning to do a complete sensor replacement next month when the part arrives. The intermittent nature of these faults makes diagnosis tricky. Try checking if your symptoms get worse in damp conditions, this helped pinpoint my problem.

Thanks for the update on your T5 sensor issues. Interesting that you also traced it back to water exposure, which matches my T6 experience exactly. The lingering mirror heating glitch you mentioned is a classic sign of partial sensor recovery. When I first tried just cleaning the connections on my T6, I had similar residual issues. The full sensor replacement you're planning is probably the right call, it ended up being the only permanent fix for my setup. The technical pattern seems consistent: moisture infiltration leads to sensor calibration problems, which then cascade into multiple system malfunctions. The visibility systems are usually the first to show symptoms, followed by climate control irregularities. One thing to watch for after your replacement, make sure the workshop properly seals around the new sensor housing. My first replacement still allowed slight moisture ingress until they applied additional sealant around the edges. This prevented any recurring electrical issues with the replacement unit. Would be interested to hear if the complete sensor swap resolves your remaining mirror heating quirks. It should theoretically restore full functionality across all affected systems.

I appreciate all the detailed feedback about humidity sensor issues and water damage. The symptoms you both described match my situation perfectly, especially how automotive sensor problems cascade through multiple systems. After getting these insights about moisture-related failures, I scheduled a diagnostic scan for next week. My visibility systems definitely act up more during wet weather, just like you mentioned. The car sensor cluster being damaged by water infiltration makes perfect sense given my vehicle's symptoms. The step-by-step approach, testing connections before complete sensor replacement, seems smart. If cleaning and resealing might fix 80% of the problems for less cost, I'll ask the workshop to try that first before changing the entire unit. Really helpful to know about proper sealing being crucial during sensor calibration and replacement. I'll make sure to discuss this specifically with the technician to avoid future moisture problems. Will update once I get the diagnostic results. At least now I have a much clearer picture of what the workshop should be looking for. Thanks for sharing your experiences with such similar issues.