I can only give you my experience this year. The bedroom unit would not come on. It sounded like it wanted to but would not. Climbed on the roof and took the AC cover off. The squirrel cage of the fan would not turn. Used some muscle to turn it just a little. I noticed some loose dirt. Bottom line it was a dirt dauber nest on the fan blades. The blades were stuck in the plastic housing the nest was hitting. Cleaned off the fan blades carefully so as not to damage the squirrel cage, put the cover back on, and the unit has run perfect ever since. May not be it, but it happened to me in Louisiana.