A 2002 is going to be 134a and NOT r-12. That changed around 1993-94 you can tell by the type of fitting for your a/c. If it has external threads it's r-12. Quick disconnect it's 134a. 134a runs at different pressure, is cheaper, you don't have to be certified to buy it from autozone.

You can do the whole thing in your garage if you have a vacuum pump, a/c flush solvent, A/C System Flush Kit and some gauges...you might even be able to fudge the gauges. But you MUST have a vacuum. Remove compressor, drier/accumulator, orifice tube(and then put the hose back together where the orifice tube WAS). Now you have two lengths and 4 outlets of pipe one goes through condenser and one goes through evap. Hook up the flush kit to air supply and get all the "glitter" out unless you enjoy changing compressors regularly. Point the hoses away form stuff you dont like covered in shiny liquid that smells like horse manure!!

All clean. New orifice tube, new drier/accumulator. Look on your old drier or somewheres else under your hood and look for how much refrigerant aka 134a and oil aka PAG-150 you need, in ounces. Pour like half in the compressor, and the rest in the line somewhere. Hook up the compressor and now you should have a closed system full of PAG oil, air, and moisture! (you can use oil to lube up seals if you needed new ones, but do NOT put the oil on the threads of ANYTHING) Without a vacuum now your a/c won't work for $hit. Pull a vacuum all night if you want, the longer the better. Then let it sit for 15 minutes and watch the gauge to see if you haev/can hear a leak(assuming you have a gauge) With a vacuum you can get a can or so of 134a right in the system without turning the compressor on. After that the compressor should suck down the rest of the 134a until you have replaced what the label said under the hood that you needed down the low side. Or alldata or Google will tell you how much oil and 134a to put in. Viola!! New a/c