It seems every month a new freon substitute comes out promising to be the
latest and greatest. As I stated previously, unlike R134, these are not
actually freons, and generally contain flammable chemicals, and all are
concoctions of assorted substances. Many state "colder than R12", though
this is more problematic than good as an R12 system is designed to keep the
coil just above freezing as it is. The statement is just for marketing to
the unknowing general public. The temp is directly related to whatever the
pressure maintained. Here's an example: an old field trick for an R22
commercial unit losing coil efficiency and freezing up would be to actually
add a small amount of R12. This would raise the boiling point at a given
pressure. But hey, isn't R12 colder than R22???? The question is
nonsensical. R22 systems usually run at about 68 to 76 psi with an ambient
of 70 to 85 degrees. R12 at that pressure is much warmer as auto systems
usually maintain about 22 - 40 PSI, varying some depending of what type of
expansion device is used and of course, the ambient temps. Low air
volume can create problems. The coil temp of the B is already kept at an
absolute low, and the coil often drops too much and can ice up. However,
the B T'stat is an old fashioned type that cycles the compressor by
measuring the air off the evap coil, not cabin temp. The new replacement
T'stat that Bob H sells allows for more fine tuning of the duration between
cycles than the OEM one.
The biggest problem with composites again even allowing many of the
marketing pitches, is that these separate over time, so when they leak out,
and almost every auto A/C system does leak, the different elements leak out
unequally, changing the formula and its performance. When recharging, its a
gimme to just dump the old charge entirely and replace it. So, whenever you
dump the charge, oil goes with it. How much is a guess, so replacing how
much oil becomes the next bit of guesswork. Be very wary of trendy
replacements. I will qualify my posts with the note that I held a Class B
HVAC commercial/residential/industrial license, and still maintain EPA
certification. My point being think carefully about using these
concoctions. If your system is relatively leak free, R 12 is still the
safest and most stable choice will give you years of service. R12 does not
wear out, and even at 25 years, is just as good as new. None of these
composites can compare. Of course, some cannot afford or do not wish to
spend the cash on the real stuff, so they may be compelled to go with a
substitute.
stephan #2821
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