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Mini split

Discussion in 'Hvacbay' started by Veloci_lobster, Jun 16, 2017.

  1. Veloci_lobster

    Veloci_lobster New Member

    Messages:
    25
    Location:
    Minnesota
    Hey everyone, I'm working on a carrier mini split 9000 btu heat pump. I'm wondering what a good low side working pressure would be. Model number is 38grqb09. Any help would be appreciated.


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  2. LemonWizard

    LemonWizard Blinky Lights Wizard

    Messages:
    2,066
    Location:
    Ohighyo
    That would depend on which refrigerant that model uses. I would imagine the normal ballpark numbers would be good if the manual doesn't specify something different
     
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  3. Veloci_lobster

    Veloci_lobster New Member

    Messages:
    25
    Location:
    Minnesota
    410a

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  4. pecmsg

    pecmsg Junior my ASS

    Messages:
    20,525
    Location:
    Eastern LI
    When in doubt pull and weigh the charge.
     
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  5. Veloci_lobster

    Veloci_lobster New Member

    Messages:
    25
    Location:
    Minnesota
    That's what I ended up doing, but the pressure on the low side was around 40. Seemed low.

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  6. LemonWizard

    LemonWizard Blinky Lights Wizard

    Messages:
    2,066
    Location:
    Ohighyo
    How long did out stay that way? Did it increase as the unit ran longer?
     
  7. Veloci_lobster

    Veloci_lobster New Member

    Messages:
    25
    Location:
    Minnesota
    No stayed there.

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  8. Veloci_lobster

    Veloci_lobster New Member

    Messages:
    25
    Location:
    Minnesota
    One of my concerns is the evaporator freezing over

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  9. LemonWizard

    LemonWizard Blinky Lights Wizard

    Messages:
    2,066
    Location:
    Ohighyo
    Do you have a long pipe run? How far above the indoor unit is the outdoor unit?
     
  10. Veloci_lobster

    Veloci_lobster New Member

    Messages:
    25
    Location:
    Minnesota
    It actually had to be below it. Good point. Pipe run is about 20 ft. We weighed it in, called for 3.1 lbs we put in 3.25. were gonna go back if there are issues.

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  11. newtech

    newtech 636

    Messages:
    831
    Location:
    Michigan
    40 psi puts you around -6 f. I would say that's a little low.
     
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  12. Veloci_lobster

    Veloci_lobster New Member

    Messages:
    25
    Location:
    Minnesota
    Any ideas why the pressure would be so low?

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  13. pecmsg

    pecmsg Junior my ASS

    Messages:
    20,525
    Location:
    Eastern LI
    Get all the info and. All tech support
     
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  14. Veloci_lobster

    Veloci_lobster New Member

    Messages:
    25
    Location:
    Minnesota
    Thanks guys

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  15. jpb2

    jpb2 Dog Tard *

    Messages:
    46,778
    Location:
    within the bounds of reality
    Most mini splits have the metering device in the outdoor unit. Pressures are not a diagnostic tool
     
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  16. tuna

    tuna New Member

    Messages:
    2,911
    Those things have so many variables, it's just hard to troubleshoot with pressures/temps. I like you would be wondering what was going on with that low pressure low side. Just see what happens...
     
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  17. Texas-Tech

    Texas-Tech Official Geezer*

    Messages:
    17,355
    Location:
    duhh
    I was going to suggest taking a good look at the blower wheel, they gunk up pretty quickly but 40 psig is pretty damn low for 410. There isn't a drier on the line is there? Not supposed to be
     
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  18. Veloci_lobster

    Veloci_lobster New Member

    Messages:
    25
    Location:
    Minnesota
    No drier

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  19. Texas-Tech

    Texas-Tech Official Geezer*

    Messages:
    17,355
    Location:
    duhh
    How old is it? Does it have a fixed metering device at the condenser or is it a newer model
     
  20. Veloci_lobster

    Veloci_lobster New Member

    Messages:
    25
    Location:
    Minnesota
    Tev

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