Performed single system cooling maintenance on 2018 heat pump. I checked amps, capacitor, filter, drains, cleanliness, refrigerant temperature, and temperature differential. The system is performing within manufacture specifications. The son spoke to me about the room still being warm. I advise that a return be installed in that to help cycle the heat out. If issue persists after return installation, it is advised to add more insulation in the attic space. The evaporator coil has minor oxidation and could use light cleaning to allow better temperature transfer. This would restore some of the system’s lost efficiency.