Again, there is a lot of options here:
1. Add more R-12 (You have to do this @ a shop)
2. Add more R-12 "Equivalent", DIY
4. Drive with windows open/Move to colder climate.
More HVAC related to come:
Replacing A/C Condenser
Here is FANTASTIC site to repair your A/C
More Coming Soon! (As soon as I figure out how to do this or write up what I already have)