Mercedes-Benz C220 Forum : “A/C service ports”

Very tricky to find.  The high pressure side is near the radiator on the left side.  The low pressure connector is off the left side of the engine, much easier to see if you remove the wiper fluid resvoir.  I can upload pics if you need.  It took me over an hour tracing the lines to find the low pressure port to refill refrigerant... then my compressor died.