Changing freon
 

I have a '77 450slc with a relatively new R-12 A/C compressor. System works but here is S. Texas it is battling to keep up. Although I can get the system charged with R-12 in Mexico it is a bit of a trip that I would rather not make. Can I (as some have told me) just charge the system with R-134? Some say the pressures required for R-134 will damage the comp. after a while. If I change the comp. to an R-134 what else should I change? Dryer? Expansion valve? Tks. for the info.

Changing freon
 

A correctly functioning R-12 system will out perform a R-134a conversion, Make sure your system is free of leaks and correctly charged, If you have an auxillary fan make sure it operates when a/c is switched on, condenser relatively free of debris, a/c controls and vents in good working order. You can still get R-12 in the states but it will be more costly than in Mexico. If your a/c system is in descent shape, you would not have to go to Mexico very often.