These unit do give problems and it sounds like you need to have the HVAC head unit repaired.
There are 2 (at least) companies who offer repair and have ads in the Roundel mag. I would try contacting them: bmwhvac.com or nhspeedometer.com and see if they can help.

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2021 X5 xDrive40i
2015 X5 xDrive35i MSport
(Traded) 2013 X5 xDrive35i