I have a 1969 Buick Riviera that I am wanting to switch from R12 to 134A. My question is can I use the same POA Valve or do I need to do one that is for 134A?
You can use the original POA valve, but for good results you'll need to have it calibrated for R134a. Classic Auto Air in Tampa will test and calibrate your POA for about $25 if I recall correctly. http://www.classicautoair.com/ Being in Texas, you should seriously consider switching to a Parallel Flow condenser. You might be disappointed in the conversion otherwise. Condenser design is the main difference between R12 and R134a systems.
Parallel Flow is what vehicles using R134a use. It's a more efficient design, so it tranfers heat better. -Serpentine- used on 50s- to ~80s R12 systems. Construction looks much like the coils on the back of an old refrigerator. One continuous path from inlet to outlet. -Tube and fin- Used on ~80s-90s R12 systems. Uses flat style tubes and more cooling fins much like a radiator. One continuous path from inlet to outlet. More efficient than serpentine. -Parallel flow-Constructed almost exactly like a crossflow radiator. A tank at each end and multiple flat tubes across. Multiple passes across the core. Maybe this will help: http://www.ackits.com/parallel/condenser1.jpg
Exactly. I wouldn't do it, no way. R134 is the Prius of refrigerants. I successfully use Freeze 12, (142B) which is almost discontinued, but can still be found. I use R12 on cars that never leak (not many)