Common R-22 Replacements Compared
Refrigerant
Notes
MO99 (R-438A)
One of the easiest R-22 retrofits.
R-407C
Common replacement, usually requires POE oil.
R-422D
Retrofit option, some capacity loss.
R-427A
Good medium-temp replacement.
For an HVAC comfort-cooling system, many technicians consider MO99 one of the better "drop-in" style retrofits for aging R-22 equipment because it usually requires fewer changes than R-407C.
My great grandparents, born pre 1900, always told me to never sleep in the light of the moon. They told me other things as well and I chalked it up to superstition. I stopped thinking that years ago and I truly believe they knew important things. I wish I had paid better attention but I was just a kid.