The regulation calls out 19 vehicle functions which must have physical controls inside the vehicle, with additional requirements about size and usability of the buttons.
Those functions include:
Turn signals
Hazard lights
Horn
PRND gear shifter
Driver assist function, if present
Windshield wipers
Windshield defroster
Power windows
Emergency call system
Power off switch for EVs


And I am providing a reasoning why they choose those but not AC.
Because it is not essential to driving, it could be seen as an overregulation to require that