After talking to Marco about his AC performance in his 70 Stage1 4 Speed drop top I figured I would make a post to help members more understand the difference in the refrigerants and how they work with there system. Your older AC system was designed to work with the refrigerant it came with and changing the refrigerant to another and expecting the same performance will not be the end result, like putting regular fuel in you Stage1 GS. First understand the pressures are higher on 134a then R-12 and the 134a system requires a larger condenser and different expansion,dryer and POA valve because of the formula of the this refrigerant to work correctly and dropping a different refrigerant will not work correctly. Another thing to condenser is the oil in the 134a is a different base then R-12 and changing over will contaminate you system because it is almost impossible remove all the other refrigerant oil and you hoses, compressor and "O" rings are made for a R-12 system. In time the incorrect oil will damage your "O" rings and your compressor. As I posted earlier the pressures are higher and this may cause problems with you original hoses and compressor. I've seen correct change overs put this requires all hoses compressor, expansion, POA valves, condenser, drier and evaporator. I've read about other drop in refrigerants and read they still use another base and will lead to trouble in time. So in short if you have a system with no leaks the R-12 would be a better choice and is still around, AL.
Good info AL. A few years ago, R134a conversion was the only good alternative in older vehicles. You almost needed to give your firstborn male child to get R-12. As the demand has dropped for R12, so has the price. Look for the price to drop more as time goes on and newer R12 equipped vehicles are retired, leaving a large supply for collector vehicles. R12 is again a viable (and preferable) choice for collector cars. Earlier this year, before AC season, R-12 was available for $10/lb. in #30 cylinders. I think we will see prices a bit lower this winter. The small cans are $25-45 each. The demand for them is higher due to their size and ease of use.
