I spent a lot of time online and on the phone today about R12 vs R134. I read every thread about the conversion I could find, called my local independent MB mechanic, called my other independent mechanic, and even spoke to a guy at H&H who handles west coast distribution for Johnsen's Freeze 12.

I still don't have an answer. The R12 is about $60 a Lb., the R134 is about $5.99 a Lb, and the Freeze 12 is about as cheap as the R134 @ $6.99.

Problems seem to be that the R134 doesn't cool as well, and will, given sufficient time kill the compressor on older systems not equipped to deal with it's higher pressure. AutoZone has the conversion kit to R134 for about $35, but my other mechanic says that I will get about 6 Mos before the compressor will die. He suggests staying with R12.

The rep for Freeze 12 says that it is fully compatible with R12, that I could just add it to my system without a purge and evacuation of the system, and it would be likely to run for 2-3 years even with a minor leak before it needs replenishment. But Freeze 12 is 80% R134 & 20% 142b. I was told by him that the 20% R142b eliminates the corrosion factor, and makes it compatible with the R12. I have a can of unused R12, and he suggests just adding it to my system as is, and running the system through the summer or as long as it will last.

The Mercedes mechanic wants to do a diagnosis for $117, retrofit the system for R134 @ $200.00, plus the cost of repairing any leaks. The other mechanic says the R134 conversion is not as good as repairing the system, and filling it with R12 at a cost of about $180 for freon, plus about $80 labor.

So, barring any further research (unlikely in my case), do I add the R12 I already have to the system, or have the system inspected and pumped down, then add the R12 with a dye to look for leaks, or do the conversion over to R134 or to Freeze 12?

Bottom line, is the 1 can of R12 I have sufficient to get the system to work? Or am I better off using it to augment the recharge of R12 after inspection and sealing?

Oh, but what about the combination marker dye and AC system sealer you can add to the system? Does it work?

So many questions, so many options...

__________________

Scott Longston
Northern California Wine Country...
"Turbos whistle, grapes wine..."