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Which Refrigerant?

Al K._2
Al K._2 Member Posts: 27
Does anyone have a way to tell wether a R12 system has been converted to R134A or not? Customer indicates it may have been done, but not sure enough to convince me either way. A gas test or an oil test that can be done on site would be good.
Al K.


  • ed wallace
    ed wallace Member Posts: 1,613

    i take it this is a car or van otherwise its r22 or r401a not sure if you can convert a house a/c system to r401a you might want to ask at hvactalk.com

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  • Glenn Harrison_2
    Glenn Harrison_2 Member Posts: 845
    There are refrigerant identifing machines out there

    for the automotive industries, specifically designed for automotive situations where a r-134a conversion may have been made but not labeled. If your not an automotive mechanic, go talk to your local mechanic and see if you can make arangements to rent their unit, or to bring a sample to them. If you are an auto mechanic, talk to your tool suppliers about one.
  • clammy
    clammy Member Posts: 3,094

    the easiest way to tell is to use a pressure temp chart for refregerants and from ambient temp and a set of gauges you can tell the refregerants standing pressure against the ambient temp and look at a pressre temp chart for r134a ansd r-22 and that should tell ya is this for automoblie or refrgerators or a dehumiderfer good luck and peace
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • Greg Swob
    Greg Swob Member Posts: 167
    Service valve ports for 134A

    are different than R-12. So far, the only ones I have seen (for automotive anyway) are a snap-type quick release rather than threaded. I don't do MVAC, but did convert a vehicle we no longer own once. All the conversion kits I found included adapter ports. I suppose these adapters could be removed and then the mystery continues. Greg
  • Al K._2
    Al K._2 Member Posts: 27

    The dillema, the quick-connect adapters are present. I'm just not convinced a conversion was done or if it was a convenience for somebody with a new manifold.
    Ed, yes, it's a car- my son's first car. Hvactalk is an option I hadn't thought of- thanks.
    Glenn, I'm a hvac-r tech (commercial mostly). I didn't know such a machine existed. If I can locate one, I'll gladly pay the diagnostic fee.
    Clammy, a sixteen-and-a-half year old's car is never at "ambient"! I did consider drawing a sample and comparing to control samples of the two refrigerants. Seems like a lot of work, though. I'll keep you posted on what I discover.
    Al K.

  • Matt Undy
    Matt Undy Member Posts: 256
    Test Kits

    There are test kits for identifying refrigerants also. Try Grainger or Maitnence Warehouse/Home Depot Supply (www.mwh.com). I'm not sure how they work but there are chemical tests out there. I can't seem to find them now, but I think I saw them somehwere...The tempurature/pressure chart may be easier, just keep in mind the mixture idea below.

    Also if I recall correctly 134a has a higher BP than r-12 (maybe a differnt latent heat too?) and doesn't remove as much heat in a system designed for r-12 as the system did with r-12 so poor performance may be a design problem rather than a charge problem.

    Its also possible that it was a retrofit by somone who didn't know what they were doing and they didn't recover the r-12 and evacuate (change the lubricant too i believe) before adding r-134a so it could be a mix of r-12 and r-134a. Somone may have also put in a hydrocarbon susbstitute wich is both illegale and very dangerous in a front end collision since it it flamable and explosive. Could also be one of the nonflamable accepted substitutes. Check the EPA website, they have accepteable substitutes listed in there somewhere.

    The comrpessors pretty much always leak a bit at the shaft seals on auto systems, correct?

    Good luck.

  • Matt Undy
    Matt Undy Member Posts: 256
    Conversion of r-22 to r-410a

    You can not convert an r-22 system to an r-10a system without significant modification, the properties of the 2 refigerants are quite different.

  • JEM
    JEM Member Posts: 7
    R12 -R134

    A1 K, If the retro service port adapters are in place take it to a local shop and have the system vacuumed down and shot up with the correct amount of R134,leak detector dye and oil. I work at an independent auto repair shop and your delima is no big deal at all.
  • Matt Undy
    Matt Undy Member Posts: 256

    Isn't mineral oil insoluable in r-134a so that you need to make sure the system was flushed of mineral oil before charging with oil compatible with r-134a? If there is reason to believe the conversion was done incorrectly then it must be flushed of oil and replaced. If whoever installed the adaptors didn't put a lable somewhere indicating the new refrigerant type, which is required when the tyep is changed, I would be very suspect of the whole job havin been done correctly.

    Let me just remind you that it is illegal to vent a charge of r-12 or r-134a.

This discussion has been closed.