That's a lot... let's start inside the space. There should be a circuit breaker at the main electric panel, a thermostat, inside the air handler is the blower motor, a few relays or a circuit board (depending on what type of unit), the evap coil, and a metering device (either a txv valve, a piston, or capillary tubes depending on the unit). Outside you should have a disconnect for your high voltage, then there's a contactor, a fan capacitor and a run capacitor (or both in one, again depending on the unit), then there's the compressor which is either a scroll compressor or a piston compressor, and the condensing coil.