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Thread: MO-99

  1. #1
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    MO-99

    Charged an old R22 unit today with MO-99. Ended up with pretty much the same pressures as R22! Was interesting to see as I've never used it before. Outdoor ambient of 80...49 degree suction line. 75psi on the low side...225 on the high. Seemed to be performing well.

  2. #2
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    Supply air temp, superheat and subcooling?

    Sent from my LM-G820 using Tapatalk

  3. #3
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    Quote Originally Posted by CEAS-AC-TECH View Post
    Supply air temp, superheat and subcooling?

    Sent from my LM-G820 using Tapatalk
    Supply air temp - cold...i didn't measure directly. I usually do. I just checked with my hand quick.

    Superheat/subcool - didn't have a mo99 pt chart handy. It had a txv. Now that I look..two different pt charts give me two different temperatures? According to one, my txv was working accordingly....and according to the other...my txv is stuck open?? Weird. Forgot to check subcool. Its got a leak. I was there converting and charging dye. Gotta go back.

    Probably 25 yr old system.

  4. #4
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    My boss tried mo99 back when r22 was really high and he had so many problems that he switched them all back at his own expense and won't touch r22 replacements ever again.

    Sent from the Okie state usin Tapatalk

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  6. #5
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    Quote Originally Posted by R600a View Post
    My boss tried mo99 back when r22 was really high and he had so many problems that he switched them all back at his own expense and won't touch r22 replacements ever again.

    Sent from the Okie state usin Tapatalk
    What kind of problems was he having? This was the first time i've used it, and it seemed to be working pretty good. R22 is on the way out...at least here in Canada. So I opted for the more affordable MO99. One thing I was thinking about is the gas charge in the R22 txv bulb when using MO99...if it would work ok. The things I read it's supposed to work with no component changes.

  7. #6
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    i have been using MO99(R438A) for over 5 years.I have not had any problems with it.

  8. #7
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    I've used mo99 quite a bit. Never had any issues what so ever.
    Only thing to take note is that suction pressure will be a few psi lower than r22.
    So if you were reading 49 deg suction then would actually be 53-55 deg.
    You don't squat with your spurs on.
    And you NEVER put the torches away before pressure testing.

  9. #8
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    Quote Originally Posted by desol View Post
    What kind of problems was he having? This was the first time i've used it, and it seemed to be working pretty good. R22 is on the way out...at least here in Canada. So I opted for the more affordable MO99. One thing I was thinking about is the gas charge in the R22 txv bulb when using MO99...if it would work ok. The things I read it's supposed to work with no component changes.
    I think it was mainly capacity problems but I don't really know. He hates it with a passion.

    Sent from the Okie state usin Tapatalk

  10. #9
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    Quote Originally Posted by R600a View Post
    I think it was mainly capacity problems but I don't really know. He hates it with a passion.

    Sent from the Okie state usin Tapatalk
    lol. My old boss didn't like it either...he said it wasn't quite the same. He did Ice plants...that were full of R22. I never used it there but we had a jug hanging around. I just do res and light commercial. No big stuff. That could be where the difference is.

    Engineering says it should work.

  11. #10
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    Quote Originally Posted by desol View Post
    lol. My old boss didn't like it either...he said it wasn't quite the same. He did Ice plants...that were full of R22. I never used it there but we had a jug hanging around. I just do res and light commercial. No big stuff. That could be where the difference is.

    Engineering says it should work.
    I just realized I was mixed up. He had problems with r422b.

    Sent from the Okie state usin Tapatalk

  12. #11
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    Ha! Turns out it was my boss not yours! Anyway...had a nice cold suction line when I left the job today.

  13. #12
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    If the vapor line temp was at 49° and you had a saturation pressure of 75PSIG. You had zero SH.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

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  15. #13
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    Quote Originally Posted by R600a View Post
    I just realized I was mixed up. He had problems with r422b.

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    I used a lot of 422 and no problems. You were not trying to mix it with r22 ?

  16. #14
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    Quote Originally Posted by oldguy1949 View Post
    I used a lot of 422 and no problems. You were not trying to mix it with r22 ?
    I am shure he recovered the r22.

    Sent from the Okie state usin Tapatalk

  17. #15
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    Nothing will be as good as the real stuff. period. The real difference is when it's 106 outside.

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  19. #16
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    Quote Originally Posted by theoldscroll View Post
    Nothing will be as good as the real stuff. period. The real difference is when it's 106 outside.
    And the condenser is dirty and the fan blade is not set to the proper depth.

    Sent from the Okie state usin Tapatalk

  20. #17
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    Quote Originally Posted by R600a View Post
    My boss tried mo99 back when r22 was really high and he had so many problems that he switched them all back at his own expense and won't touch r22 replacements ever again.

    Sent from the Okie state usin Tapatalk
    Yup. Unless I’m replacing a compressor, R22 goes in. I’ve used MO99 with some inconsistent results. RS44B works well, but the issue is I’m not carrying 5 different flavors of retrofits on my truck so on the off chance I can recharge an 18 year old system. This late in the game, aside from commercial systems, R22 systems are at the age of replacement if a major refrigeration repair is needed.

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  22. #18
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    Quote Originally Posted by CircusEnvy View Post
    Yup. Unless I’m replacing a compressor, R22 goes in. I’ve used MO99 with some inconsistent results. RS44B works well, but the issue is I’m not carrying 5 different flavors of retrofits on my truck so on the off chance I can recharge an 18 year old system. This late in the game, aside from commercial systems, R22 systems are at the age of replacement if a major refrigeration repair is needed.
    I have been trying to convince him to let me try and repair a leak on a 15 ton package unit we take care of and convert it to 407c or whichever one it is that everyone says is the best.

    Sent from the Okie state usin Tapatalk

  23. #19
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    Quote Originally Posted by beenthere View Post
    If the vapor line temp was at 49° and you had a saturation pressure of 75PSIG. You had zero SH.
    That's what I thought. It was fluctuating between 49 and 52. The system has a new txv...there should be superheat.

    I used the dew point column on the pt chart for checking the saturated suction temperature on mo99...and 75PSIG was 49 degrees.

  24. #20
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    We used "NU22" (422B) in the beginning of this mess and was told to be the next best thing....
    No problems EXCEPT capacity loss. Most systems are over sized, but...
    Hit a couple that were sized "correctly" and got in a bind. Dropped it like a hot bolt!
    Went to 407c on "replacements" and never turned back.




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    Life is too short, Behappy!
    TFMM

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