When I was in Afghanistan, they had these sorts of air conditioner/heat pump units in the base containerized housing units. (People often referred to such a heating/cooling unit colloquially as a "Chigo", after one of the most common manufacturers.) They normally worked reasonably well, even when it was 110 Fahrenheit outside. When problems usually arose was when people set the thermostat too LOW, and the evaporator coils actually iced over. Then the air flow would get blocked and the affected room would get super hot. People would have to turn the cooling mode off and wait for the ice to melt before it would work again.