VW Golf HVAC Blower Failure, AUC Sensor Guide

The symptoms match what happened on my VW Passat 2020 TDI. The complete blower failure turned out to be more than just an air quality sensor issue. In my case, the problem stemmed from a faulty wiring harness connection to the climate control module. The repair required accessing the blower motor assembly behind the dashboard. The main culprit was corrosion in the plug connectors, which interrupted communication between the climate control unit and the blower motor. This is actually a common failure point in VAG vehicles. A proper fix involved: Removing the glove box for access, Testing the air conditioning sensor circuits, Replacing the corroded wiring connector, Checking the blower motor resistance, Running a full climate control diagnostic scan This was not a quick fix and required specialized diagnostic equipment. The complete repair took about 4 hours, but prevented potential major electrical issues down the line. A faulty connection can cause permanent damage to the blower motor if left unaddressed. Best to have this checked by a shop familiar with VAG climate control systems. The problem will likely get worse if ignored, possibly leading to complete HVAC system failure.

Thanks for sharing this detailed info about the wiring harness issue. I had almost the exact same problem with my Golf last winter, complete blower failure and initially thought it was just the cabin air sensor acting up. Had the same repair done with the corroded connectors being the root cause. Would you mind sharing what the total repair cost was in your case? My repair happened over 6 months ago and I am curious to compare prices. Also wondering if youve had any other HVAC sensor related issues pop up since getting it fixed?

Just had my VW back from the shop last week and can update on the AUC sensor fault situation. The total repair cost came to 95€, which covered fixing the faulty cable connection to the climate control module. Much cheaper than expected since no parts needed replacement. The blower has worked flawlessly since the repair. No other cabin air sensor issues or climate control problems have emerged. The mechanic confirmed the original fault was caused by a loose connection that was disrupting communication between the AUC sensor and the main control unit. This turned out to be a simpler fix than my initial worries about needing a complete sensor replacement or extensive HVAC system repairs. Having a technician properly diagnose the specific connection issue saved both time and money. The climate control system is now functioning exactly as it should. Worth noting that these sensor faults often stem from connection problems rather than the actual components being defective. Getting a proper diagnostic scan helped identify the exact issue quickly.

Just got my Golf back from the repair shop yesterday and wanted to share the outcome. My auto recirculation system is working perfectly now! The total repair came to 380€, more than I hoped but worth it for a proper fix. Turns out the air quality sensor was fine, but the connector had completely corroded through. The mechanic showed me the damaged parts and explained how moisture had gotten trapped in the wiring harness. They had to replace the entire connector assembly and clean up the surrounding area to prevent future issues. The repair took about 3 hours total. They did a full diagnostic test afterward to ensure all the HVAC sensors were communicating properly. The BMW AUC system is now working better than it has in months, the auto climate control responds immediately and the blower motor runs smoothly at all speeds. No regrets going to this new shop. They clearly knew what they were doing with VAG climate control systems and took the time to explain everything. Much better experience than my previous repair attempts.