Cooling Coils or AC Evaporator Coils is a component of the HVAC system. It comes in two forms. One, that refrigerates directly from the AC unit. The AC unit outside is piped straight to the DX unit (a direct expansion air conditioning unit) within the AHU (an air handling unit) or the fan cooling unit. When it's a refrigerant-based it has an expansion valve, which is regularly placed directly outside the coil.
*Common for small shops or buildings.