If evaporator starts to freeze up the ice accumulated serves as an insulator and the temps go up. If you turn it off and let ice buildup melt the unit will work fine again until it refreezes.
Check if unit has a device to prevent ice build up. If so, it is not working. If warm moist air is entering the area of evaporator coil, that could also be causing the buildup.
Answers & Comments
If evaporator starts to freeze up the ice accumulated serves as an insulator and the temps go up. If you turn it off and let ice buildup melt the unit will work fine again until it refreezes.
Check if unit has a device to prevent ice build up. If so, it is not working. If warm moist air is entering the area of evaporator coil, that could also be causing the buildup.