Originally Posted by Nick-B
Only half true. R134a does run slightly lower pressure but only on the evaporator side. The condenser side definitely runs higher pressures. Check any AC temp/pressure chart.
While I don't have a lot of experience with auto a/c I have 20 years experience with r134a in fridges, walk in coolers, prep coolers, pop machines, walk in freezers, ect. and the high side pressure is never more than a few pounds of the high side of the old r12. So you statement of significantly higher is not true