ke6dcj,

If I were you I would go back to R12. BTW, yes 80 to 85% of the R12 quantity is what you need in 134 if you stay with it.

To go back to 12, you need to flush EVERYTHING to remove the oil, remove compressor and flush the PAG out of it using mineral oil, don't use solvent in compressor, put compressor back in place, put in the correct amount of mineral oil, evacuate and charge with R12. Also replace any switches or devices that you changed due to 134 pressure differences with appropriate parts for R12. Make sure you get ALL the flushing agent out of the system. This can be difficult in the evaporator and condensor, particularly the condensor.

Also, in hot weather, a 24 hour evacuation is not necessary. The hotter the components, the quicker the moisture will boil out under vaccum.

Best of luck,