Strange since one adds refrigerant at the low-side port. If you didn't have a gage attached to the high-side port, perhaps the Schrader valve had been stuck open and the oil flowing thru it lubricated it enough to close again. If you had left the system with no pressure for a long time, atmospheric moisture can get inside which is absorbed in PAG oil to form corrosive oils. Some people then fill with a HC refrigerant, find a leak in corroded metal, like an aluminum condenser and blame the refrigerant. That would have happened with any refrigerant which pressurizes the system.I tried one of the propane "Enviro- something" brands.
My 2000 Dakota puked it back out.
I put 134a back in and it's been "better" but not as cold as new.
Funny, as it actually vented out the high side connector.
I thought it had blown a seal, but after it coughed up all that "refrigerant", the port appeared to be OK.
I can't explain it, but that's what happened.