Capacitors and contactors wear out first
The run capacitor gives the compressor and fan motor the extra push they need to start. It weakens slowly, so the system still starts, just with more strain each time, until one afternoon it doesn't. The contactor is the switch that sends power to the outdoor unit, and its contacts pit and burn from years of closing and opening. Either one failing can look the same from inside the house. The indoor fan runs, but the outdoor unit stays silent.







