I studied this thread from June 2005 on Refrigerants.
It mentions R134 R12 and "Freeze 12".

Ac Cold At Last!! 83 Sd


I have a 1980 300D that has an empty AC system. (It worked fine when last
used - had it recovered before pulling engine).

Putting in a new Receiver/Drier and going to recharge it.
I have converted other R12's to R134 and have never had a problem.
Whatever loss there has been in cooling, it has been acceptable.
I am no AC expert, just a DIY.

1. Usually I do not use gauges, but this time I thought I would
go ahead and purchase a gauge set - most of you use gauges ?
Anybody got numbers for hi and lo pressure ?
2. I will not ask about Freeze 12 - that discussion has been covered
in earlier thread - But, LarryBible, what about "Enviro-Safe".
My gut experience has been that anything New,Improved,Works Like,
better than, is a bunch of hooey (not worth it, hype). So I am
inclined to completely dismiss it and stick with approved R134.
Thoughts ?

3. I see used R12 recovery equipment for under $100. I certainly
cannot afford R134 recovery equipment. But what a shame to
see this stuff go to waste. Is there any way to get approval for
use in R134 ? It would be great to have a R134 recovery system
in my home tool shed.
I thought you were not supposed to mix R12/R134 recovery,
but this listing is for a Dual Purpose R12/R134 recovery machine.

http://cgi.ebay.com/ebaymotors/SKYE-MULTI-REFRIGERANT-A-C-RECOVERY-MACHINE-R134A-R12_W0QQcmdZViewItemQQcategoryZ63700QQitemZ4572806843QQrdZ1QQsspagenameZWD1V

Some new loophole/regulation ?

__________________
80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250