To recharge or Rebuild A/C?

I know... I have searched and couldn't find conclusive evidence either way, but I was wandering if one could tell if an R-12 system just needs to be topped off or actually rebuilt i.e. flush, replace drier, and rings, etc. etc. etc.? Any help would be much appreciated. The system ran fine last year, when I bought it, and now the compressor kicks on but doesn't cool. Again Thanks

[brewtoo]

Do you see bubbles in the sight glass when the compressor is running?

If the system is low on refrigerant then there is a leak. Find the leak, fix the leak and recharge.

Good luck,