I have a window unit that is 220v and is about 3 months old. It was doing just great until this last bout of hot and humid weather. Cools real well until the afternoon then it blows warm air. I hosed down the outside radiator part, didn't see a lot of dirt, but cleaned it real well. Cleaned the filter, it wasn't very dirty. Didn't help. I can shut it down for at least an hour and it will blow cold, but not for very long. If I leave it off long enough it will start cooling but usually very late in the day. Can't remember exact btu but I think was around 23k. We are looking at 3 more very hot months before it hopefully cools down in october. What to do?