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  1. #1
    Join Date
    Aug 2018
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    Noise at evap coil

    Hi, I was cleaning a residential ac unit last week, and I noticed something weird.
    Whenever the compressor started, there would be a loud whooshing noise at the evap coil, sorta like opening a valve on a tank, except muffled. The noise lasts about 2-3 seconds each time.
    This is a 2.5 ton 410 unit without a txv, about 2 years old.
    Speaking to the homeowner It has done it since new. The unit cools well, and I didn’t hook up the gauges to it.
    Any idea what might be causing this?

  2. #2
    Join Date
    Mar 2014
    Location
    Ottawa,ON
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    242
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    Is this a heat pump or straight ac?


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  3. #3
    Join Date
    Aug 2018
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    Thread Starter
    AC


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  4. #4
    Join Date
    Mar 2014
    Location
    Ottawa,ON
    Posts
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    So did it work fine after u cleaned it? Sure that noise wasnt a big hole in the evap ?


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  5. #5
    Join Date
    Aug 2018
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    10
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    Thread Starter
    Unit cools good. I only cleaned the condenser coil, the evap was clean.


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  6. #6
    Join Date
    Dec 2004
    Location
    Chicago area
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    6,135
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    Thats the sound of gas blowing through the metering device. At start up, its mainly gas in the liquid line.


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  7. #7
    Join Date
    Jun 2017
    Location
    Central FL
    Posts
    17
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    That's normal, gas being pumped through your liquid line as heatingman said. You're never going to start a unit and not heat the refer moving. A constant loud swish might indicate an issue though.

  8. #8
    Join Date
    Dec 2009
    Location
    maroon lazyboy
    Posts
    2,096
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    You can hear it on expansion valves also. Listen for the liquid seal to hit, the “dry” TXVs really whistle.

  9. #9
    Join Date
    Aug 2018
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    Thread Starter
    Quote Originally Posted by knave View Post
    You can hear it on expansion valves also. Listen for the liquid seal to hit, the “dry” TXVs really whistle.
    I guess I’ve never heard it that loud before, I was just wondering if it’s normal. I suppose it is. Thanks!


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  10. #10
    Join Date
    Jan 2013
    Posts
    55
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    Check the refrigerant pressures, sometimes it’s other things like low refrigerant which can indicate a possible leak,non condensables or not topped off since it’s fairly new.

  11. #11
    Join Date
    Sep 2018
    Location
    San Diego
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    34
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    Quote Originally Posted by heatingman View Post
    Thats the sound of gas blowing through the metering device. At start up, its mainly gas in the liquid line.


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    ^^^^ THIS ^^^^ Probably a non bleed

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