Replacement Freon for R-12

[19Charger68]

I have heard that there is a substitute for R-12 Freon that will work in an original AC system.  Do any of you know what it is and where it can be found, or does it even exist?

Thank you,

Bruce

[1BAD68]

R134

[John_Kunkel]

There are several, this is one:

http://autorefrigerants.com/co00030.htm

Keep in mind that all so-called replacements are blends of different refrigerants with different sized molecules, the difference in the size of the molecules means that the refrigerant with the smallest molecules will leak off first leaving an imbalance that prevents simply "topping off". If the system leaks down it must be completely purged and refilled.