thank you, gary, for your detailed answers. i'm not sure how to send you a private message but i am happy for you or your friend to email me at critters911@gmail.com
the car is a 1997 and the a/c worked fine until late summer 2010. when i realized it wasn't working i took it into my mechanic, who charged it and it worked for a very short while--maybe a couple of hours. he said it wouldn't last and it didn't. the green light was still coming on when i pressed it until the past couple of weeks.
when my car was totaled, it was hit on the driver's side although mostly at the back. that was in july 2008 and the a/c worked for two more years.
based on the info that it worked for a while after my mechanic charged it, does that indicate the system sealer may work?
i can add air to a tire so i will give it a try.
in the meantime, if your friend is willing to take a look at the car, i'd really appreciate it. and thank you again for your help.