Quote Originally Posted by oscarvan View Post
And I am no expert so I would like to believe you as it would buy me (a lot) of time on my units. I was just reporting what the various technical sites were telling me. But you sent me back in the rabbit hole and I found this:

https://legacyac.com/things-to-be-aw...-refrigerants/

But also this.... so it appears that MO99/R438-A is a viable option, with some caveats.

https://heatingcooling.fergusonhvac....ofit-solution/
Good for you researching - I was trying to do the same but got derailed with an issue of my own.