OK , what about R22 in an automotive system designed for R12 ? Partial
replacement , IE top off a system that's shutting off due to low pressure at
the receiver can ? I know there are kits out there to convert R12 car AC
systems to R134A , which also has higher working pressures ...
Legally speaking, not permitted.
Technically, R22 has much higher
pressures. If we were on a desert
island outside US territory, I'd
sure try it, if it was the only
stuff I had. Might satisfy the
pressure switch. There would not
be as much refrigerant in the system,
so it might not cool quite as well.
R12 and R22 both miscible with much
the same lubricating oils, so that's
Pro A/C is R-134a.
I don't know how well the Pro A/C would connect up with the port on your
home system, but as a "top-up" R134a doesn't seem to work well enough to
be worth the hassle.
Propane, on the other hand, works very well as a top-up replacement for
Because there is no oxygen in the refrigeration circuit, propane is no
more dangerous than R22 in your A/C unit. All the FUD about using
propane in R22 systems came from when people wanted to use it in cars,
and there are hot surfaces and a relatively closed under-hood engine
compartment where a leak could possibly cause ignition. In a home R22
system with slow leak and better air circulation, it's improbable that
any propane leak would be a combustion risk. In other words, in a home
R22 system that has a slow leak that needs a recharge only once a year
(or once every several years) propane is an excellent choice for top-up
because such a slow leak would never cause a buildup of combustable
concentration if the leak was inside the home - and naturally there
would never be any risk if the leak was outside (say in the compressor
or outside coils).
Getting back to R134, here's the best thread I've found that's similar
to what you're asking about:
The guy writing that topped up his home system with R134a because he did
not think he could get his hands on R22. After he learned that he could
get R22, he evacuated his system and recharged with R22 and no harm done
to the system because of the R22/R134 mix.
=========26-05-2010, 05:49 PM
Re: Residential R-22 system. HO added 134a
I have searched the internet far and wide to see if anyone had anything
to say about adding Automotive R134A to R22 Residential Split System. I
know I screwed up, acted first and investigated after.
I never found anything conclusive about PAG oil contamination of my R22
system, everyone talks about the other way around. MO contamination of
Everything I read about flushing (many problems in itself and chemicals
involved), drilling hole in hermetically sealed compressor to drain oil
and change oil sounded too extreme. Especially with no good data one way
or the other about effects of any left over pga oil. at least not that I
could find. The R134A and PGA oil has been mixed in with R22 and MO most
of last season. No noticeable ill effects that I can see.
I have now evacuated at 29" for about 18 hours and recharged back to
System is running perfect and superheat numbers match manufactures
Outside Dry Bulb: 78F
Outside suction temp at condenser unit: 59
Suction Pressure: 70 PSI (41F Sat. Temp)
Liquid Pressure: 235 PSI
Inside Dry Bulb @ intake of evap: 78F
Inside Wet Bulb @ intake of evap: 65F
Manufacturer Superheat Charging table calls for SH of 18 at these
1989 bryant 2 1/2ton spit system 591A030
I guess I am just going to cross my fingers and hope that introduction
of R134a and PGA oil were taken care of by deep vacuum and will not
cause compressor failure. Hell I have already got 22 years out of this
unit and it still runs like the day it was installed. If it fails, I'll
bite the bullet and have entire new system installed.
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