Oops, you were referring to CONDENSERS, not COMPRESSORS, as I erroneously pointed out.
From the A/C posts I've read, those who have done the conversion say that R134a doesn't cool as well as R12.
Again since I'm not an expert, I don't know if there is a way to "hot rod" the A/C...
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car