What happens when one uses a Chlorinated Refrigerant (i.e. CFC or HCFC) in PAG oil made for R-134a systems?
PAG OIL (Polyalkylene Glycol) Refrigerant oil made for HFC (e.g. R-134a) systems CANNOT tolerate even minute amounts of chorides, such as from aluminum chloride "coatings" inside pipes that formed from the original R-12 charge or having over .5% or more of "chlorinated refrigerants" in the system. Chlorinated refrigerants include the CFCs (chlorofluorocarbons) and HCFCs (hydrochlorofluorocarbons). R-11 (flush) and R-12 are CFCs. R-11 is extremely damaging to PAG oils, more so than R12. This information dates back to 1990-1991.
HCFCs include R-22, R-124, R-142b (blend components used in R-406A/Autofrost, Frigc FR-12, Freeze12, Freezone RB276, R-414A (GHG-X4), and R-414B (ICOR HOTSHOT).
Use of any of the above refrigerants or blend components in a system with PAG oil will mostly likely destroy the oil. There have been some attempts to make PAG oils to withstand chlorides, most notably the "Daphne" brand. The test sheet I saw still showed slight darkening of the PAG oil (Daphne brand) when mixed with R-12. Other brands of PAG oils turned black. When one services a car, one usually does not know if it contains Daphne PAG or not.
Not all CFCs/HCFCs are the same reactivity in destroying PAG oil. R-11 (the old "flush") is the most reactive by far, and R-124 is one of the least. Actual break down times will be related to ambient temperature and operating temperature as well.
A 16fl oz bottle of GM Delco "Refrigerant Oil R134a Systems" (other numbers on bottle: 1#12356151 Gr. 8.8 1#15-118) was purchased at a local auto parts store. The label also had the information "Contains: Polyalkylene glycol-New Jersey Trade Secret, Registry number 027586004-8550P).
A newly developed PAG oil, called "Daphne" or "Double end capped" PAG oil has been shown to be able to withstand chlorinated refrigerants, even R-12, MUCH better than conventional PAG oils. However, Daphne or Double End Capped PAG oils are very expensive and are not commonly used. The above paragraph quoted from ICOR's web page says "Don't be concerned about the new Double End-Cap PAG oils", where they should be saying that Double End-Cap PAG oils are the only PAG oils that HOTSHOT will be stable in.
A test vessel was charged with 5ml of GM PAG oil, then evacuated to below 400 microns of vacuum to remove air and moisture, and then charged with about 20ml of ICOR HOTSHOT in liquid state.
|Vessel charged with 5ml of
GM DELCO PAG Oil. Note
light blue color. Also contains
a small piece of aluminum
A/C pipe. No refrigerant.
|5 ml of PAG oil with
ml of ICOR HOTSHOT
refrigerant added. Still has
faint light blue tinge color.
|One day later, oil is
to decompose and darken.
|One month later, the mixture
has turned dark orange, a sign
of failed PAG oil.
|Same as prev picuture, but
with the refrigerant removed,
leaving just the oil that has
now turned "muddy" black.
As one can see, the PAG oil breaks down with HOTSHOT refrigerant. A second round of tests was done with a piece of aluminum evaporator pipe present, showed a faster darkening of the oil (it was as dark after 3-4 days as was the previous test (above pix) was in 1 month. No evidence of corrosion to the aluminum though. All CFC, HCFC refrigerants (R-11, R-12, R-22, R-124, R-142b, R-401A/B/C, R-406A/Autofrost, R-409A, R-414A (GHG-X4) and R-414B (HOTSHOT), Freeze12) are expected to produce similar PAG oil breakdown (in non Daphne/Double End capped PAG)..
TO safely run in [non Daphne/Double end capped] PAG oil, non chlorinated refrigerants, such as HFCs (hydrofluorocarbons - e.g. R-134a), pure hydrocarbons (explosive), or blends of HFCs or ethers must be used.
AUTOFROST GHG-X7 and X8 (Cooltop) are designed to replace R-134a. They require PAG or POE oils and WILL NOT work in mineral oils used by R-12.
In recent times, the automotive aftermarket has been promoting a "flush" for servicing all types of A/C systems (including R-134a/PAG) that contains R-141b, a chlorinated solvent. This seems to be an ill advised move, considering that chlorinated substances often cause degradation to most PAG oils.