There seems to be a somewhat widespread issue with bad evaporator temperature sensors in X cars of recent vintage (according to SC technician I spoke with). I just had mine replaced.
The telltale (if you don't have developer mode access) is even if you increase airflow to 11, there's barely any. The car thinks the evaporator froze and enables evaporator freeze protection (Without telling you!)
The workaround I heard about is to basically turn off A/C but leave ventilation on full blast for some time.