Hopefully someone who knows something about the manual controls will chime in. You should probably get a wiring diagram and theory of operation for the manual controls. It still could be the aux fan but that will be hard to eliminate without having a known good one to plug in.

I see in your first post INPA is showing the A/C input and compressor, that is from the DME then ? Is there even an A/C module ? I know the Evap temp sensor is different for the manual controls so maybe there is not even an A/C module ??

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1988 325is (purchased new) sold
2004 X5 3.0 2005 X3 2.5
2008 X5 3.0 (new to me)