After 25 yrs, our AC doesn't cool right. I've cleaned the outside unit, changed the air filter, etc. I imagine it is R-12 coolant. If its needing recharged, what are my options, and how much can I do to facilitate repairs and save money? Can more modern coolant be used? What about alcohol-type coolants? Any ideas appreciated. Thanks. Wrong forum, sorry. Hope I get the hang of this. Lot of good brains out there I could use.