Last summer my a/c was working but not as good as I wanted.I took it to a mechanic friend who recommended converting it to R-134a.I did some research on this and found that although it would work, the R-134A runs at higher pressures which may be too much for some older sytems, and also would not cool as well.It would be better to Just upgrade the whole a/c system to a True 134A system($1300)This is alot of denero but I live in Texas and Gots to have the A/c.I continued researching a bit and came across this stuff called "Freeze-12" Which is a cfc free alternative to R-12 that would mix with and perform much like r-12.So, I got hold of some and added a can to my system.The difference was obvious right away, with a 10-15 degree drop in temp of cold air from my vents.It has been over a year now and a/c is still working great.And I have an extra can on standby just in case.I do not recommend any one else do this without plenty of research on your own because the guy who told me they( freeze 12 & r-12)would mix happened to be trying to sell me the stuff.All I knew was others had done it and in the year since I've put mine in it's still working great and there seems to be no signs of damage to my system.The only reason I would have any concern is that another guy ,who was selling a similar r-12 replacement,told me that freeze12 will eat up seals and o-rings, but I have seen no signs of that.I just went with my gut at the time,not really knowing what to believe and what to dismiss as sales tactics and so far all is well.If you're at a point where you're considering replacing the entire sytem anyway, then what do you really have to lose in giving it a try.Freeze -12 is cheap and available on Ebay.I even have an auto parts place nearby that sells it and you dont need any kind of licenses to buy it.At least not on ebay or here in Texas.My a/c still blows cold and the $1300 they want to replace the system still sits in the bank.Good Luck To All.