First off, hello. To the mods, I think you should create a new Forum titled HVAC. Bunching the HVAC in with general electronic and infotainment makes searching a pain. End of tiny rant.
I would like to ask the community if anyone else has seen issues with your HVAC system. As an example, I have my 2017 Limited parked in the garage, only heated to 40F. I have turned the blower to off, and left the mode in Mix (floor/def). In the morning, I open the garage door, get in and press the button to start the engine. When I move the blower to the first detent, the indicator for the AC comes on amber (which on the 7" screen shows MAX AC). Then I have to manually push the AC button to cycle the indicator to green (screen shows ECO AC), then push again to turn it off. This should not be normal for these temps. I have also noticed this happens when parked outside with the recent warmer weather (located in WI). I also see the recirc indicator on sometimes when this happens. It is a manual, single zone system. I know from experience that even the manual controls have some smarts built in to allow automatic functionality in the background.
I should also say that I work for an automotive supplier (TRW) that designs and builds both the software and hardware that controls HVAC systems for other car manufacturers (currently not developing/producing any (current) GM systems).
I have only had this car for a couple of weeks and this is making me scratch my head. Any and all assistance is appreciated.