Puzzled

[TWP723]

We have a 2021 Montana with dual quiet AirXcel ducted ac units. The bedroom (cool only) unit works fine. The main in the living area will not blow cold on "cool low". On "cool low", it blows warm air. I'm guessing from outside. But works on "cool high" and "cool high auto". Am I missing something? Is it normal for this to be? Or should I expect it to blow cold air, regardless of the setting.