92 ford exploer

A better question might be what you are trying to accomplish. There is no such thing as the 'entire ac unit'. The A/C system consists of numerous components, located in different places. Some of them are easier to replace than others. If this vehicle still uses R12 (Freon) and you are thinking of converting to R134a, there may or may not be a need replace a couple parts, but certainly not the 'entire unit'.