Just did this a couple weeks back. The fill port is on the driver side behind a plastic splash guard near the suspension. The port on mine was either right on the AC compressor or very near it. The compressor is on the underside of the driver side front part of the engine and is easily accessed once you remove the plastic panel covering it, just 2 or 3 tiny screws hold it on. jack up the car, no need to remove the wheel, just work underneath, engine OFF until ready to charge/Test.
You will need the modern R134(?) type port adapters instead of the older R12. Since R12 is pretty much illegal for home mechanics, the stores sell only the correct coolant and connectors.
Get a coolant charge that also has lubricant in it since when you lose charge you lose lubricant too. You might even get a charge that has untraviolet(Black Light) dye to spot leaks. Just use a hippie black light to spot the leaks.
You should buy a recharge kit with a guage so you can check to see if you really need a charge.
To do the job properly you need to evacuate the system which means you go to a certified mechanic with the machine to suck out all your expensive coolant, and then put it back in without air and charge you lots. The home recharge kits are fine for when you are just low but are not good when your system is empty or has air in it.
The engine must be running while testing and charging so watch what you are doing.
Works good for me on at least 4 cars I have owned using R134 that needed a "top up" charge.
