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Thread: TXV Problem?

  1. #1
    Join Date
    Nov 2008
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    TXV Problem?

    A few weeks ago a tech came out to check everything on my Ruud heat pump as a preventative and he said all was well. Now that I'm using the heat I have noticed a problem. When the unit comes on the liquid line starts warm then in about a minutes time you can hear what sounds like a vibration and the liquid line becomes cool. The temp exiting the air handler mirrors the drop in temp, then the temperature starts rebounding slowly to what it first was and the liquid line warms up as well. For example, unit comes on to 95 degrees exiting handler, one minute passes, liquid line grows colder, temp from handler drops 6 to 7 degrees, vibration noise goes away, temp starts increasing a degree each minute, temp reaches 95 degrees again, temp continues to increase depending on outside temp. Can anyone explain what is taking place here?

  2. #2
    Join Date
    Dec 2005
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    1,918
    First of all this problem cannot be caused by the tech, who did the maintenance. It is the internal-part problem.

    My guess is the internal check valve of the indoor unit (if equiped) is not open 100% causing the slamming noise. Give it a couple days of run-time before calling the service company.

  3. #3
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    Nov 2008
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    I didn't mean to imply that the tech had anything to do with it but wanted to use his visit as a reference that all of the readings were good. It is not an actual slamming but more of a vibration, this has been going on for some time with the results I had previously posted. Do you believe that the txv is could be faulty? If so how long does it typically take to replace it. Thanks again for the info.

  4. #4
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    Quote Originally Posted by carlb7 View Post
    I didn't mean to imply that the tech had anything to do with it but wanted to use his visit as a reference that all of the readings were good. It is not an actual slamming but more of a vibration, this has been going on for some time with the results I had previously posted. Do you believe that the txv is could be faulty? If so how long does it typically take to replace it. Thanks again for the info.
    A heat pump has 2 TXVs (or other expansion devices). One at the indoor coil and one at the outdoor coil.

    In heating mode, the TXV at the outdoor coil regulates refrigerant flow. The TXV at the indoor coil should be wide open in heating mode.

  5. #5
    Join Date
    Nov 2008
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    162
    Thanks Gary. I see the txv on the inside unit but do not see one on the outside. Could the valve on the inside malfuction and cause the problem I'm seeing? I guess the outside unit is a fixed metering device so I don't beleive it would be the cause.

  6. #6
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    Jan 2004
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    It may not be caused by the metering devise/devises.

    There is an electrical device that can cause it.

    A tech needs to check it.
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  7. #7
    Join Date
    Nov 2008
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    I've got a call out for a tech to come out tomorrow. Could you elaborate on the possible electrical problem? One other observation is when the unit shuts off you can hear low pitched squealing in the line, like fluid being restricted but squeezing through, at least thats what it sounds like. You all are the pros so I'm just looking to be educated.

  8. #8
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    Not all HP's have one.
    Have him check the CCH.

    If he doesn't know what that is, he's the wrong tech.
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