Just wanted to update. Replaced auxiliary fan with new. No change.

Pretty Crazy! New OE ? Does INPA show the request for A/C from the button ?

Clutch control sequences. I'll would take a look at wiring.

Is there a rear fan installed?

New aftermarket. INPA does NOT show the request.

Do you mean inside the cabin? Not that I'm aware of.

I would concentrate on figuring out why the DME doesn't see the A/C button, or even defrost button?? It still would be nice to know if there is a controller involved with the manual A/C and how it is wired, and if there is a bus involved, any chance you can get a hold of that info ??

What module are you reading to get evap temp etc. ?

So I had a look in the Bentley manual and it's all there! ;) The IHKR(manual control) is a module itself just like the IHKA. BOTH operate the compressor clutch directly so you probably are operating the compressor and monitoring functions with INPA through the IHKR not the DME. You really really should have a Bentley manual!

Do rear vents have a speed dial? If so, it has a fan in the console. Your model shows it's an option.

It looks like the the DME can "signal" the IHKR to turn off the compressor so would be really good to know what module you are in when turning the compressor on. There could be something going on with the connection from the DME to the IHKR or maybe even a "data bus" issue which might be explained by rain into the open sunroof.