404a or R134???
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Thread: 404a or R134???

  1. #1
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    Replacing a defective hermetic compressor that is noisy and not pumping. The refrigerant that was used was Hot Shot. The oil in the new compressor is Polyester and I want to use R404 or R134 for proper oil return. The unit is Medium cool and the thermestat is usually set at about 38 degrees.
    The present compressor CS20K6E TF5-270 was not a burnout, just defective valves and not pumping at all. Both suction and discharge same pressure, The unit is 3 phase. Will change both suction and liquid filter driers and blow lines out with nitrogen.

  2. #2
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    Smile 404A or 134A

    What was the original refrigerant used in the system (before Hot-Shot) go with that. Flush out the system,then use suction and liquid line driers. Also when charging it is now reccomended to charge liquid through a drier after evacuating to 500 microns(no lower compressor oil boils at 200 microns).
    RAM Teaching Tomorrows Technicians Today.

  3. #3

    Re: 404A or 134A

    Originally posted by icehouse
    compressor oil boils at 200 microns).
    Where is this info from?

  4. #4
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    Don't know what the previous refrigerant was. The present compressor has a serial number of 95K68705H. Looks like copeland recommend R-404a.

  5. #5
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    I think you need to call Copeland to make sure you have the correct compressor. 134a and 404a are for different applications, and run different pressures. If the refrigerant was Hot Shot, then it was probably R12, so 134a is probably what you want. You need to check that the evaporator and condenser is properly sized if you're changeing to 404a, and also change the TXV.

  6. #6
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    The new compressor comes with polyester oil. and it is a medium temperature compressor. I must use a refrigerant that will mix properly with polyester. This leaves R507, R22, R134a, R404a.

  7. #7
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    I understand that, but each compressor is rated for different applications such as "medium temp 134a," "low temp 134a" and "low temp 404a." Just because the refrigerant is compatible with the oil, doesn't mean that it will act correctly in the application.

    Basically, 134a is a replacement for R12, and 404a is a replacement for 502. You wouldn't put R12 into a 502 system, as it wouldn't work. In the same respect, 134a would not work properly in a 404a system.

    You said that it was a medium temperature compressor. It's not often that you see 404a used in a medium temperature application, and since you said that the old unit had Hot Shot in it, I'd assume that you need 134a.

    I hope I'm clear. It was hard for me to put my thoughts into words.

  8. #8
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    I downloaded the datasheet from copeland and it is rated as HFC, R404-A, 60 Hz, 3 - phase, 200-230 V, Extended Medium Temp. What is the difference between Medium Temp. and Extended Medium Temp.?

    [Edited by sgosine577 on 02-16-2005 at 08:36 AM]

  9. #9
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    404A or 134A

    Extended means it will cover a greater btu rating. Tecumseh calls theirs the plus line ie 1/3+ 1/4 + for a little more btu rating. If it had "Hot-Shot" in it, then the previous mechanic did not do his home work like you did. Then you must flush the system, remove the expansion valve or if a capillary tube system back flush it.
    RAM Teaching Tomorrows Technicians Today.

  10. #10
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    Dec 2004
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    This compressor is rated as a; High temp R-134a, A Medium temp R-22, A Extended medium R-404 / R-507.

    What's this about no less than 200 microns????

    Oil doesn't boil in any micron range.
    Be Careful, The Toes You Step On Today May Be Conected To The A$$ You Have To Kiss Tomorrow.

  11. #11
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    They are not bad gases. Get used to them, I don't see them leaving very soon.

    All change is not bad.
    A Diamond is just a piece of coal, that made good under pressure!

  12. #12
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    I would go with 404.......it works very well.
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

  13. #13
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    Hold your horses now, guys.........

    As I read this thread, it has yet to be established what refrigerant this system was originally set up for. (We all know it wasn't built for Hot-Shot).

    There's no nameplate info given or TXV identifiers noted anywhere. We don't even know if this compressor is a proper replacement for the job.

    It was mentioned that this CS20K6E is multi-rated for R134A HT, R22 MT and R404A EMT (Extended MT). The original post says this is a cooler, so if you check capacities at +20F SST/ 120F SDT for each of these refrigerants we find that R22 and R404A are about equal at 20,000 Btuh and R134A comes in at around 12,000 Btuh. That's a big difference.

    We need a lot more info on this system before we start recommending what refrigerant to be putting in it.

    Sgosine557.....How about some info on the TXV, the evaporator coil or the original condensing unit dataplate?

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