The compressor is located outside the home on residential systems and is part of the condensing unit. The high-pressure vapor passes through the condenser coil where it gives off heat to the atmosphere. The condenser coil usually surrounds the compressor. A fan blows air on the condenser coil to assist the heat transfer process.
Residential systems use an air-cooled condenser coil.
Once the refrigerant leaves the condenser, it is now a high-pressure liquid. It passes through an expansion device and becomes a low pressure liquid. Sometimes the AHU also has an oil or gas burner built into it so it can be used for heating as well. A fan in the AHU pushes warm air from the conditioned space past the evaporator coil, the air gets cooler and the refrigerant evaporates to a low-pressure vapor. Hence the name evaporator coil.