I'm trying to fix my window unit. It's an LG LWHD1200R. It was working great 'till yesterday (100°F +) when I got home and found that the upper right quadrant of the evap coil had frozen. Specifically the second coil on the right side. The lower coils are not even getting cold. The fins are a bit clogged in parts, but clear over all. Could this be just dirt? Or could it be a bigger issue? I would take it to a pro for servicing, but I don't have the money at the moment, and it's getting real hot out there. Any help troubleshooting and fixing this unit would be greatly appreciated.