They do have different "snap-on" connectors in that the high side and low side are significantly different in diameter.
Ted is right:
>
> R134a system MUST have a different (snap on) fitting by law. You can,
> however, have the thread on the internal side of fitting, which is used for
> attaching the cap. For retrofitted systems you also MUST install permanently
> the new fittings when retrofit to R134a by law.
>
> Alex
>
> > > What are the fittings like that you use to induce refrigerant? If they
> > are
> > > ones that you thread a hose onto
> > > then the system is R12. R134a systems use fittings that you snap on,
> > > somewhat like a compressor line.
> > > Needless to say when you convert, you must change the fittings. > > >
> > > Regardless, if there's mechanical contamination (dirt, metal fragments,
> > > etc.) in the system, you have to
> > > flush it with solvent.
> > >
> > > Ted
> > >
> > >
> > > > One thing you didn't mention: Does the 1993 have R12 or 134? > > >
> >
> > Not entirely true.
> > My 95 caravan uses R134a and both fittings are threaded as there is a > small
> > black cap that screws on when you are done to keep the fitting clear of > > debris.
> >
> >
> >
>
>