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Thread: Scroll Flutter

  1. #1
    Join Date
    Jul 2009
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    Question Scroll Flutter

    First time poster. WHat UP?!??!

    Alrighty then.. I'm doing a side on a residential split-system. I was called to the job because it wasn't cooling. Upon arrival I hooked up and found a low suction pressure boiling off around 30(F). The hi-side gauge was saturating around 102(F). An excessive amount of water was coming off the indoor coil and the suction line wasn't sweating at all.

    What might be most important: the hi-side reading was fluttering(?).

    It's a mild flutter on a Copeland scroll with a piston-type metering device. The system runs on R-22, so the readings didn't seem far off considering the 85 degree ambient. I added a little over a pound of R-22 to see how it would respond and was able to gain some pressure on the low side, going from 30 to 40(F) degree boiling point. The hi-side didn't show much reaction, a slight increase at best: Condensing now around 105(F), still a mild flutter.

    Now I might have continued to add but I opted to watch my TD instead. I found that it went from about 7-8 to barely 5, with still an excessive amount of condensate coming off the coil.

    Maybe I should have continued to let the system run to bring down the RH, but I thought, "why make this guy continue wasting power with a 5-degree TD?"

    I told him to turn it off for the night while I did a bit of research on the flutter I found on the hi-side. Thus far I've found that a solenoid-valve could be causing the compressor to flutter this way, and that it's not that uncommon to find this action in copeland scrolls.

    Here are some factors that might help you guide me in the right direction:

    Suction Line Temp: 75.2(F)
    Low Side Sat: 40(F)
    Superheat: 35.2(F)

    Liquid Line: 78(F)
    Hi-Side Sat: 105(F)
    Subcool: 27(F)

    Ambient at time of reading: 87(F)
    Return temp: 79.5(F)
    Supply temp: 74.3(F)
    TD: 5.2(F)

    Air Handler's 3-Ton "Goodman" (High Eff) with Piston-type metering device
    Condenser's 3-Ton Unit with a Copeland Scroll.

    I am new to the site. Not trying to get DIY info, but rather, suggestions. I hope this is okay. I believe I've covered most bases neccessary, but will gladly try to provide more when prompted. Your suggestions are greatly appreciated. Expect to see more questions from me down the way.


  2. #2
    Join Date
    Aug 2003
    Fort Worth, TX
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    I would go for the recovery bottle. Like pronto.

    Get your post count up to 15 so you can apply for pro member status. You can then access the pro tech forum where we can discuss troubleshooting matters like this at length. Here in the resi section we're limited by the DIY concern/rule/context.
    Building Physics Rule #1: Hot flows to cold.

    Building Physics Rule #2:
    Higher air pressure moves toward lower air pressure

    Building Physics Rule #3:
    Higher moisture concentration moves toward lower moisture concentration.

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