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  1. #1
    Join Date
    Jan 2005
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    Columbia, Mo GO, TIGERS
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    899

    whats low side test pressure on a domestic refrigerator?

    after you get it isolated, what's low side test pressure on a "typical" domestic refrigerator? (you know, Frigidaire, and the like, garden variety?)

  2. #2
    Join Date
    Oct 2002
    Location
    Lexington, NC
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    5,193
    Depends on the temp of the box. Once it is cooled down to around 0, you should be in the 0 to -1 psi range on 134a.
    The main thing is to keep the main thing the main thing!

    If "the grass is greener on the other side", it likely has been fertilized with Bull$hit!

  3. #3
    Join Date
    Nov 2008
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    Hudson Valley, NY
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    203
    Batdude it sound's like you are leek checking a system
    bring it up to 100 p-s-i leave it there as long as you can then you will know what is next to do
    I did use J-B weild to fix a leek on an aluimin evaportor just pulled a vacium on that system for about an hour charged system up been working for four year's now WATCH NOW I WILL CALL THE BOX IS BLOWING HOT AIR

  4. #4
    Join Date
    Oct 2002
    Location
    Lexington, NC
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    5,193
    I appologize. I misunderstood the original question. The test pressure should be found on the unit info sticker where you will find the charge info. The last one that I did was a fridgidare and it was listed at 125 or 150. I actually put a charge on this unit of 150 for 24 hours and it never budged. This same unit has leaked down twice. I hope you have better luck.
    The main thing is to keep the main thing the main thing!

    If "the grass is greener on the other side", it likely has been fertilized with Bull$hit!

  5. #5
    Join Date
    Jan 2005
    Location
    Columbia, Mo GO, TIGERS
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    899
    thanks for that, yes. The low side pressure is so low that leak checking low side while running is futile, seems to me.

    Guy has a used appliance store. Says he has about half a dozen newer, in otherwise good shape, leakers. Asks me can you find and repair the leaks. (me thinking aluminum evaporator coils leaking means him trip to scrap yard) He's got the money I will find the time.

    Looked at one today. Runs and runs, freezer temp 21 degrees, evap barely frosted at inlet, amp draw .53, suction line temp at compressor about 10 under ambient, hot gas temp about 15 over ambient. (from memory here, notes in jalopy) Acts like she has leaked her juice, didn't see any kinked liquid line and no temp drop through filter drier.

    So, I spy copper. Have braze, will travel. (well, yeah, after a pierce and recovery, of course.) Isolate high and low sides, put in schroeder fittings, trace refrig and Nitrogen 400 psi here I come I wanna hear that ***** hiss

    well, I was leak checking a resi split one time, phone rang and I got distracted, actually did put 400 psi plus into evaporator. yikes. bled it off quick and everything was ok (I think. fixed leak, it cooled great, held charge) but I don't plan on doing that any more. Would be hard to explain.

    Am told they have some kind of epoxy for patching aluminum. Mickey mouse, but it holds for a year or two, maybe, they say. Anyone try that stuff?

    Wonder what factory charge is on these things? One guy says to gas it until the whole evap coil frosts, if the suction line frosts you've overcharged.
    They say high side saturation's about 130 degrees. Low side about 10 below. Wonder how much to weigh in to get started. Obviously no luck yet in obtaining mfg. specs.

    Have a textbook(Refrigeration & AC, 3rd. ed, by ARI, p.418) which says, "standard conditions", at 90 degree ambient, oddly--- superheated suction gas and subcooled liquid temps both 90 degrees. Refrigerant not specified.
    That room there is 65 degrees. Anyone know how to calculate/predict gas and liquid temps under those conditions? (maybe sh and sc reduced as a function of the ratio of absolute temps? a guess. are they linear in proportion to the (ambient) "load"? probably not) Another good reason to wish summer would hurry up.

  6. #6
    Join Date
    Oct 2002
    Location
    Lexington, NC
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    The 90 degree ambient temp should be for an A/C unit. I feel pretty confident that the refrigerator manufacturers design for indoor temp of around 70 or 72.
    The unit I charged only held 4.2 ounces of 134a. The sticker should be located right inside of the refrigerator section on the lefthand side at the top if it is a fridgidare.
    I wonder if your budy is charging to frost the evap coil with or without the fan on? I will assume without because you can't really see the coil in most of these units without the fan assembly attached. If you can, ask him. I believe he is correct about the freezing of the actual suction line, so perhaps he is correct with this other method. Weigh in is definetely the way to go if possible.
    The main thing is to keep the main thing the main thing!

    If "the grass is greener on the other side", it likely has been fertilized with Bull$hit!

  7. #7
    Join Date
    Jan 2005
    Location
    Columbia, Mo GO, TIGERS
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    information on the unit, you say?
    what a mind-blowing concept. hah. dumba** me look, no find. have to check the bottom, didn't think of that today. or maybe its lost. didn't see sticker or decal at all except homeowner info like cubic feet, etc. in the box.

    has a Tecuseh compressor, on it had no FLA or RLA, only LRA which was 21.
    thought that odd. should be able to look that up from number, at least.

    so I gather that low side can handle 100 psi no sweat? that ought to be a gob. thanks, all

  8. #8
    Join Date
    Oct 2002
    Location
    Lexington, NC
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    5,193
    Quote Originally Posted by batdude View Post
    information on the unit, you say?
    what a mind-blowing concept. hah. dumba** me look, no find. have to check the bottom, didn't think of that today. or maybe its lost. didn't see sticker or decal at all except homeowner info like cubic feet, etc. in the box.

    has a Tecuseh compressor, on it had no FLA or RLA, only LRA which was 21.
    thought that odd. should be able to look that up from number, at least.

    so I gather that low side can handle 100 psi no sweat? that ought to be a gob. thanks, all
    When you do go back to look, revisit that homeowner info in the box. Look really hard to see if possibly you see some signs of the faded info you are wanting.
    The main thing is to keep the main thing the main thing!

    If "the grass is greener on the other side", it likely has been fertilized with Bull$hit!

  9. #9
    What's the big secret or is it that none of the internet professionals know the answer? Here it is from Frigidare Service Data Sheet #218758400 and these pressures work for most residential systems using R134a refrigerant @ 65*F Ambiant .
    Low Side Pressure:
    Cut-in = 6 to 13
    Cut-out = -2 to +2
    High Side Pressure: 105 - 115
    Wattage: 150 - 220
    Amps (Running): 1.3 - 1.8

  10. #10
    Join Date
    Jan 2013
    Location
    florida
    Posts
    756
    are you looking for pressures to test for leaks, or actual running pressures ? personally, i wouldn't pt 400psi in anything...

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