I looked around and DO NOT USE FREEZE12!! The oils I was talking about dont mix with the refrigerant which is what you need to have happen to keep the compressor from seizing. Freeze12 seems like it would work in a R134a system because the refrigerant have similar properties so if you do a retrofit it will work but if you go through all that effort you shouldjust use 134.

Mike

 

It isnt HOTSHOT it is something different hotshot is similar to R12 but not the same and I think you need a HVAC liscence for that too.

R406a is the same as R12 as well.

 

I dont know if R406A is available to the general public. We all have lisences here and I am a mechanical engineer so we all can get the stuff so it never crosses my mind.

 

I found this on the net:

FR12 is crap, It need POEoil (carcinogenic), and boils at a higher
temperature. Read the following, which was taken off the net ..


FR12, RB-276 (Freezone) and Freeze12, have pressure-temperature
curves (evap temps) which are too low, which makes them too warm,
often 5-8 degrees warmer than R12.

Freeze12 and Freezone are about 80% R134a! R12 (at 1 atmosphere)
boils at -21.6 F, and R134a boils at -14.9 F (warmer than R12
already), so these guys add about 20% R142b, which boils at
+14.4F, making the mixture even warmer! Frigc FR-12 is 59% R134a,
39% R124 (boils at +10F), and 2% N-butane (boils at +31F). How can
that be colder than R12? It isnt.

When using FR-12/Freezone/Freeze12, the low pressure switch needs to
be replaced or adjusted from 24 PSIG to about 14 PSIG, or else
performance will be pretty bad. Even if it is changed to 14 PSIG,
the cooling capacity (quickness of the cool down) will still be lower
than R12, due to lower mass flow (lower pressures, move less molecules
of gas). If one has a common "variable displacement compressor",
such as a GM V5, there is no low pressure cut-off switch for normal
compressor cycling. These compressors are set internally to maintain
28 PSIG on the suction line. Using one of the above refrigerants
will result in 6-8 degree warmer air than R12 under the best of cases.
Variable displacement compressors are difficult or impossible to
adjust on their setpoint pressures. If the low pressure switch
(in CCOT cycling clutch systems) is not changed, all three of these
refrigerants will constantly cycle the clutch, often wearing it out
in a couple of months.

None of these refrigerants are very miscible (dissolve in) mineral
oil used in R12 systems. It is necessary, for oil to return from
the evaporator to the compressor, that at least 10-15% of a
refrigerant's
components must be able to dissolve well in mineral oil. R-134a
has ZERO miscibility in mineral oil. R-124 (39% of FR12) is almost
nil. R-142b is similar to R-22 in mineral oil miscibility, "fair
to poor". Freezone adds 2% of some lubricant to try to compensate
for poor mineral oil return, Freeze12 is the about same refrigerant
without the additive. What happens with repeated recharges with
Freezone causing oil buildup? Too much oil can break compressor
valves (oil can't be compressed).

Intermagnetics General (mfgr of Frigc) stated in a full page AD
in the "Air Conditioning, Heating, and Refrigeration NEWS", circa
the 3rd week of Jan 1996, that POE oil had to be added when using
FR-12 - an admission that FR-12 doesnt carry R12 mineral oil well.


What happens to oil return when using these systems. Some will
still work fine.. The return path from the evaporator to the
compressor is short or downhill, and the oil will probably make it
back ok, but if the path is long and/or uphill, it may not. Some
systems have only 6-8 Oz of oil, and the compressor may run dry
(and fail) if the oil doesnt make it back. This may take 1/2 to
two months for the oil to migrate out. The 2% N-butane in FR-12
is not enough to carry all the oil when all the other components
do not carry oil. I have even tested 5% isobutane in 95% R-134a
in an engineering oil-return test stand, and it did not work well.
One does not know which systems will carry oil and which ones won't
with limited mineral oil miscibility refrigerants FR-12, Freeze12,
Freezone, and HOTSHOT.

 

Agreed I was attempting to not go as indepth but that was a very accurate and complete anwser.

R406A is the way to go to be the most compatible with R12 but to be honest with you R12 is still being sold and will be sold for a long long time you just need to find a HVAC tech that can get it.