I've had issues on a couple of our BMW where the car apparently thinks it's a different temp inisde and changes the fan speed making it not achieve set speed.

I think you can real-time read the flap % with foxwell so try that. Also try using auto everything and see if you get proper airflow. Manually setting only gives you 100% or 0% flaps. Auto can stop anywhere

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)