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Re: 81 300SD A/C retrofit to R134a

So, are you saying you didn't change out the valves or the o-rings or any of those? just drained the R12 and charged R134a?

I have an 87 300E

aprox 3/4 of the full charge stated on the R12 label. > > did not change any switches on mine. > > mine was an 84 300sd > > the case, minus a few cans! > >
Reply to
purplegrog
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Depending on how long you want the A/C runs or how well you want the job done.  In principle, yes, evacuating R-12 then charging R-134a is the main thing to do, but consider these scenarios:

  1. The system is 15 to 20 years old.  How much longer can these rubber rings last?  The ring probably costs each from dealer.  Replacing every one you open adds no more than for the total job.  How much extra time do you want to spend the NEXT time to replace these?
  2. R-134a molecule is smaller the R-12.  It cannot circulate the mineral oil (used in R-12 system) well and that is why ester or PAG oil is used in R-134a.  A compressor without oil dies pretty fast.  The mineral oil takes up space and it won't help cooling so it should be sucked out as much as possible.
Reply to
Wan-ning Tan

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