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  1. #1
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    Sep 2010
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    Probable refrigerant in old cooler

    Hello,

    I came across a pie case today that is low on charge. I could not find any markings that would tell me what refrigerant is in the unit.

    The compressor is a RSN4-0050-IAA with a serial number from 88. This would lead me to believe R12

    TXV is a FJ-1/2-C which is tagged as R12, R134a, and R401a.

    I hooked up my Neutronics Refrigerant ID and it did not ID it as R12 or R134a but instead came up with:

    DET-1 = 5.7%
    DET-2 = 49.0%
    DET-3 = 45.3%
    DET-4 = 0.0%
    NON = 0.0%

    I know it wouldn't recognize R401a but it should have picked out R12 or R134a. I don't know if anyone else has one to compare readings.

    The PT chart for the three is all pretty close, so I don't know if I could do a standing pressure test to differentiate.

    I have never ran across R401a before.

    Anyone have any thoughts?

  2. #2
    Join Date
    Dec 2014
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    401a (mp39) is very common around here. It works well.
    That's pretty old system there, so can you go with 409a? Or hotshot maybe, so you can stick with mineral oil?
    Otherwise switch to 134a. Be sure to add a suction filter. You'll lose 4% capacity (approx.)
    You can use the r12 txv, altho it's a good time to install a 134a txv.

    Might be a good time to discuss new equipment.


    Sent from my SM-G950U using Tapatalk

  3. #3
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    Sep 2010
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    Thread Starter
    Thanks for the input. I did forget to mention the only part number I found close to the condensing unit was "Structural Concepts Part Number 85296" It may be just for the frame the condensing unit sits on.

    The TXV is already rated for r134a. Maybe the simplest place to start is to pull the compressor and dump the oil, add POE, and convert to R134a.

    I don't want to invest a grand on a jug of refrigerant that I'll never sell.

  4. #4
    Join Date
    Dec 2014
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    With that 134a txv it may have 134a in already then?
    Some one changed the txv.
    The velocity in close coupled cases will allow you to run 134a with no oil change.
    At least I've found that to be true.
    You could add a few ounces POE or Supco 88 too tho.



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  5. #5
    Join Date
    Mar 2008
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    Structural concepts is a manufacturer
    https://www.structuralconcepts.com/
    Honeywell you can buy better but you cant pay more

    I told my wife when i die to sell my fishing stuff for what its worth not what i told her i paid for it

  6. #6
    Join Date
    Aug 2002
    Location
    Southold, NY
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    Probably was R-12 but with no markings its anyone's guess. Pull the remaining charge, change the drier and use any of the R-12 replacements. Unless you change the oil avoid R-134A

  7. #7
    Join Date
    Jul 2000
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    Guayaquil, EC
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    Since you can't ID which refrigerant is in there, you must recover and charge with the best replacement option, which in this case would be R134A. As mentioned, a close-coupled system (especially one where the evaporator is above the compressor) will work well with just a partial oil change to POE or by adding some Supco 88.

    Whenever I came across an unmarked system, the unknown refrigerant got changed out with the proper refrigerant and marked. "When in doubt, pull it out."

  8. #8
    Join Date
    Dec 2014
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    Quote Originally Posted by mjohnson2981 View Post
    Hello,

    I came across a pie case today that is low on charge. I could not find any markings that would tell me what refrigerant is in the unit.

    The compressor is a RSN4-0050-IAA with a serial number from 88. This would lead me to believe R12

    TXV is a FJ-1/2-C which is tagged as R12, R134a, and R401a.

    I hooked up my Neutronics Refrigerant ID and it did not ID it as R12 or R134a but instead came up with:

    DET-1 = 5.7%
    DET-2 = 49.0%
    DET-3 = 45.3%
    DET-4 = 0.0%
    NON = 0.0%

    I know it wouldn't recognize R401a but it should have picked out R12 or R134a. I don't know if anyone else has one to compare readings.

    The PT chart for the three is all pretty close, so I don't know if I could do a standing pressure test to differentiate.

    I have never ran across R401a before.

    Anyone have any thoughts?
    Curious. How did you happen to have that refer identifier?
    Not a common tool I think.

    Sent from my SM-G950U using Tapatalk

  9. #9
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    Sep 2010
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    Indiana
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    Thread Starter
    Quote Originally Posted by icy78 View Post
    Curious. How did you happen to have that refer identifier?
    Not a common tool I think.
    Not all that common but I did buy one about 8 years ago. I keep it on the van with me for situations like this.

  10. #10
    Join Date
    Sep 2002
    Location
    Virginia
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    409A was the worst refrig made , if you cant keep that coil squeaky clean she will run hot in a minute

    I use 134A when converting from 12

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