To be certain:
* Consult your owner's manual: This is the best resource for precise location information.
* Look for a smaller port with a service cap: The low-pressure port will usually have a blue cap (though this isn't always the case). Look carefully near the drier/accumulator for a fitting that looks like it's designed for connecting an AC charging hose.
* Refer to a repair manual or online diagrams: Websites specializing in automotive repair (like Haynes or Chilton manuals) often have diagrams showing the exact location of AC components. Searching for "2002 Ford Explorer AC system diagram" might yield helpful results.
Caution: Working with refrigerant requires specialized tools and knowledge. Improper handling can lead to injury or damage to the AC system. It's best to have an experienced professional handle AC system service and recharging.