Where is the fill port for ac on 2004 mountaineer?

The fill port for the air conditioning system on a 2004 Mercury Mountaineer is located on the low-pressure side of the AC system. You can find it near the front of the engine compartment, typically on the larger diameter line that runs from the compressor to the evaporator. It is usually capped with a blue or black plastic cap. Always ensure the engine is off and use the proper refrigerant type when refilling.