Q8 Climate Control Failure: Poor Heat Distribution Alert

Had identical symptoms on a 2015 Q7 3.0 TFSI last winter. The climate control system showed poor heat distribution despite the blower motor running normally. After diagnostic tests, the main issue was a faulty wiring harness connecting to the air distribution motor. The HVAC unit was functioning, but the temperature regulation was compromised due to this connection problem. The repair involved accessing the climate control module behind the glove box and replacing the damaged wire connections. While this sounds simple, it required partial dashboard removal for proper access to the temperature flap actuator wiring. This turned out to be a common failure point. The repair was not particularly complex but required specific diagnostic equipment to properly calibrate the air distribution system after the fix. The temperature regulation returned to normal immediately after repair. Most importantly, delaying the repair could have led to complete failure of the climate control system, potentially affecting the defrost function which is a safety concern. The blower motor and other core components were fine, it was purely a connection issue. My suggestion would be to have a proper diagnostic test done at a workshop with VAG-specific testing equipment to confirm if your Q8 has similar wiring issues.

Thanks for sharing your experience with the Q7 wiring issue. I am finally tackling this problem with my Q8 since the windshield fogging is becoming unbearable, especially during cold mornings. The symptoms match perfectly, poor heat output and air circulation problems despite the blower working fine. Accessing the heater core through the dashboard panel sounds like a big job. Would you mind sharing the repair costs in your case? Also, has everything worked flawlessly since the fix or have you noticed any other climate control quirks?

Just got back from having the exact same repair done on my Q7. The defrost air distribution flap fault has been completely resolved, the ventilation system is now working perfectly. The repair shop found a faulty cable connection to the flap actuator, which explained all the air circulation problems and windshield fogging issues we were both experiencing. Total cost came to 95 Euro for fixing the cable connection, which was much less than I initially feared. The heater core and other components were all fine, it was purely an electrical connection problem affecting the climate control system. Since the repair, the heating and defrost functions work flawlessly. No more temperature control issues or foggy windshield problems. The air distribution is now even throughout the cabin, just like when the car was new. Getting this fixed was definitely worth it, especially considering how crucial proper defrosting is for safe driving. If your symptoms match what I experienced, you are likely dealing with the same issue. Would strongly recommend getting it checked soon before winter makes the problem more noticeable.

Thanks for the input. I finally went ahead and got my Q8 fixed today. The ventilation system diagnosis confirmed what you all suggested, a faulty wiring connection to the temperature flap actuator was causing the climate control issues. The repair took about 3 hours. They had to remove part of the dashboard to access the HVAC unit, but the actual fix was straightforward. Total cost came to 110 Euro for parts and labor. Much better than I expected after seeing the dashboard dismantled. The windshield fogging has completely stopped now. The temperature regulation works perfectly and hot air flows evenly through all vents. Really glad I got this sorted before the weather gets colder. The small electrical issue could have led to bigger problems if left unchecked. For anyone else facing similar symptoms, get it checked early. These wiring problems seem common and the fix is relatively inexpensive when caught early.