go to some place that sells car stuff and find an AC recharge kit. it is not a r12 to 134a conversion kit, just an AC recharge kit. you can buy them just about anywhere that sells car stuff but i suggest an auto parts store for a better selection. buy the kit with the special new refrigerant stuff, this stuff does make a difference, i have it, my AC is very cold now.
anyways, that kit will have everything you need to get started and good instructions on how to do everything.
if you find out your system is still fully charged and its not as cold as you want and you want to replace the refrigerant with all new stuff then you will either need to bleed it out yourself, which might actually be illegal, i think this stuff is bad for the ozone, so yea either do it yourself, or go somewhere and pay them to purge the system for your so you can put the new stuff in.
my system was not empty, i put a can or 2 of the new stuff in, i dont remember exactly how much, been about 2 years since i did this, but it made a significant difference. im sure if you have a full system of the new stuff it would be even colder.
the most important thing is to not over fill the system. before you add any coolant check the PSI during a few cycles of the compressor. the pressure will go up and down as the compressor is on or off. make sure as you are adding refrigerant that you are checking the PSI during the right point in the cycle. the instructions in your kit will walk you through all of this. ive done it on 3 cars, worked like a charm every time.
