[alfa] re: Air conditioning question (No Alfa content)

["John S." <roadtrip999@xxxxxxxxxxx>]

Joe mentioned about alternative refridgerants, so I'll give you my take on 
them, FWIW.

As a matter of fact, I also have an 85 Cherokee with the V-6 and A/C. About 
3 years ago the R-12 charge went low enough to become ineffective. The 
system has sat for 3 years dormant. This year I decided to try an 
inexpensive alternative to R-134. Since the Jeep has 200k miles on it now, I 
didn't want to spend several hundred dollars to convert to an R-134 system . 
. . which would probably need a parallel flow condenser to work well.

At any rate, I had what was left of the system evac'd (only about 4 lbs of 
pressure in the system = empty). Some places will do it for you for free 
since the recovered R-12 is saleable.  I hooked up a vacuum pump and pulled 
the system down for an hour or so and checked for obvious leaks. There were 
none. Next I let the vacuum come up to 10" as recommended by the alternative 
refridgerant. The one I used was Enviro-safe. The advantages of HC 
refridgerants is that they're not controlled by the EPA and are 
environmentally friendly. I added in the amount recommended by Enviro-safe 
(1/3 the normal R-12 charge by weight) and the system cooled just like R-12 
does. This refridgerant is completely compatible with all R-12 seals, 
compressor, mineral oil, etc. (unlike R-134). So far the charge has held, 
but even if there's some seepage, the stuff is cheap, non-harmful to the 
environment and only costs about $5 a can (=1lb of R-12). Hi and Lo 
pressures are fine and according to the manufacturer, takes less hp to turn 
the compressor. It is flammable, but less so than R-134, and at a something 
like 1500F.

However, that said, if you have most of the R-12 still in your system, a top 
off charge may be all that you need. HOWEVER, MIXING REFRIDGERANTS WITHIN 
THE SYSTEM IS ILLEGAL AND NO A/C MECHANIC WILL LIKELY WANT TO EVACUATE YOUR 
SYSTEM WITH MIXED REFRIDGERANTS UNLESS HE HAS A VERY SPECIAL RECOVERY 
MACHINE. The manufacturers of the HC refridgerants tell you to NOT mix 
refridgerants. Evac your system first, then fill with HC. If you want to 
know more about the alternative refridgerants, do a web search. There's lots 
of info out there on them.

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