Quote:
Originally Posted by Mobile Master Tech
During the R12 to R134a auto air conditioner retrofit boom, we all originally thought that all the mineral oil had to be removed otherwise catastrophe would result. As it turns out, it is ok to leave the majority of the mineral oil in the system, as long as the required amount of the new lubricant that is miscible with the new refrigerant is added and the volume of remaining oil doesn't take up so much space to cause problems (usually not an issue). The non-miscible oil just gets pushed around the system along with the miscible oil and refrigerant. I have personally kept tabs on hundreds of retrofits with nothing other than a dryer/fitting/labeling change and the addition of the correct oil-no failures due to the retrofit.
If the components work ok within the operating characteristics of the changed system, the desiccant/dryer (if installed) is compatible with the new refrigerant/oil, and the proper oil for the refrigerant is added, I think you are unlikely to see problems with refrigerant conversions.
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This is good information...
Wish we had a list of refrigerants and the oil types that are miscible with them.
As I understand it, mineral oil is miscible with R22 and R290 (a happy coincidence) ... beyond that I am not certain.
If you happen to have this info, please share.
Best,
-AC_Hacker