with the precautions of unique fittings and mandatory
on-vehicle lables, A/C service providers still risk
costly contamination if a mixture of refrigerants has
been introduced into a vehicle's A/C system before it
gets to them. For that reason, many are routinely using
SAE-approved refrigerant identifiers--devices that "sniff"
and identify specific refrigerants. If it cannot determine
the exact type, it will indicate that the system contains
an unidentified refrigerant or mixture of refrigerants.