try tapping the duo valves with a soft hammer to unstick them. If that doesnt help their pintles have broken off inside.

Lots of lookup material online to repair them, BMWs also use similar design and part (just throwing it in for broader search).

To verify such, press the EC button and aim the target temperature to be ambient temperature outside or lower, you should not be getting heated air from the vents at that time. If you get heated air your duo valve is stuck/broken.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)