Single-ingredient refrigerants like R12 and R134 do not change composition
under any ordinary conditions in a system.  Those composed of mixtures,
Freeze-12 among them,  present the possibility of differential leakage of
the components through hoses and seals, and at least potentially of
components pooling in different parts of the system so that if you withdraw
some (but not all) it will cause the mixture to change.  I have no idea how
much problem this is in practice -- it's one of the industry's stated
objections to refrigerant mixtures.

david

At 17:02 8/15/2000, Mick Kalber wrote:
>It was God knows how old.  Can freon go bad over time, lose it's charge, or
>it's good as long as it hasn't leaked out?  If it was bad, that might
>explain why the tech couldn't get cold air until he added an additional
>three pounds of "good" freon to the system.  He put the old freon back in
>the system, then began to add the new.  Techie says no... if it's present,
>it's good, it it's missing, it's bad.  Can't be there and be bad.  Using
>R-12 by the way.
>
>   Whadayathinkabouthat?

David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"