Hummer EV's HVAC System Dead After Service Visit

The HVAC sensor failure symptoms match what happened with my GMC Hummer EV SUV 2023. The cabin air sensor and AUC system completely shut down, similar to your situation. The root cause was a faulty wiring harness connection to the blower control module. Several pins in the main connector had corroded, disrupting communication between the HVAC sensors and the climate control unit. This affected both the blower operation and the auto recirculation functionality. A complete diagnostic revealed multiple sensor fault codes pointing to the wiring issue. The repair required removing the lower dash panel and replacing the entire wire harness assembly along with the connector. While not a complex fix, accessing the components was time-consuming due to their location behind the dashboard. This is considered a significant repair since it affects multiple vehicle systems. The blower and sensor issues can lead to poor cabin air quality and potential moisture-related problems if left unaddressed. The repair shop should perform a full HVAC diagnostic scan to confirm if your issue matches these symptoms before proceeding with parts replacement.

Thanks for sharing that experience with the wiring harness issue. Those AUC sensor problems can be really frustrating. Had the exact same symptoms with my Hummer EV last winter, blower dead and climate control acting up. Just wondering how much you ended up paying for the full repair? Also, has the HVAC sensor system been working properly since the fix? Been a few months since my repair and while the main issue is resolved, sometimes the auto recirculation still seems a bit sluggish to respond. Would be helpful to know if any follow-up maintenance was needed in your case.

Happy to report my climate control system has been working flawlessly since getting the AUC sensor connection fixed. The repair was relatively straightforward, just 95 Euro to fix a defective cable connection to the component. Much simpler than initially expected. The air quality sensor and auto recirculation now respond immediately when conditions change. No sluggish behavior at all from the cabin air sensor. The repair shop mentioned these connections can deteriorate over time, affecting how the climate control system reads air quality changes. No follow-up maintenance has been needed in the 6 months since the repair. The HVAC diagnostic showed all systems working within normal parameters. If your auto recirculation still seems slow, might be worth having the air conditioning sensor calibration checked, sometimes they need adjustment after the initial repair. The entire climate control system is much more responsive now. Definitely worth getting it properly diagnosed rather than living with partially functioning sensors.

Thanks everyone for the helpful feedback. Just wanted to update on my repair experience. Took it to a certified shop last week and the issue was exactly what was described, corroded wiring to the climate control module. The repair was quick but accessing the components behind the dash took most of the labor time. Total cost came to 120 Euro for parts and labor. The HVAC sensor diagnostic confirmed multiple fault codes related to the wiring harness. Since the fix, the blower and cabin air sensor are working perfectly. The auto recirculation system responds much faster now when detecting outside odors. The climate control maintains consistent temperature and the air quality monitoring seems more accurate. Really glad I got this sorted before winter. The technician mentioned the corroded connections could have eventually affected other systems if left unfixed. All the HVAC diagnostic readings are now showing normal values. Big improvement from the sluggish performance I was experiencing before. No more issues with the AUC system or blower functions.