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Thread: Bad TXV?

  1. #1
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    Bad TXV?

    I was on a A/C not cooling call. It was a trane running R-22. It called for 10 subcooling which it had. But the low side I noticed was 30 degrees, a little low. The unit had a clean filter. I added about a pound of freon just to see if getting it to that 40 would make a difference, but the gauge stayed on 30. All that happened was my high side went up. So at that point I stopped. I took a reading of the suction line at the condensing unit and it was 70 degree. So I ruled it as a bad TXV. Is this a correct diagnosis?


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  2. #2
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    Sounds like it. Sub cool will likely rise as liquid begins to back up against valve. As long as good airflow I would say yes, bad txv - or clogged inlet strainer at txv


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  4. #3
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    Was the evap coil clean?

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  5. #4
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    Quote Originally Posted by CEAS-AC-TECH View Post
    Was the evap coil clean?

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    I never checked it. The customer said he cleans the trane clean effect filter regularly.


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  6. #5
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    Quote Originally Posted by EseLuisito View Post
    I never checked it. The customer said he cleans the trane clean effect filter regularly.


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    Trust but verify.


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  8. #6
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    Regularly to a customer might mean once a year.

  9. #7
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    If there was an airflow problem you would have a low superheat but you don't, you have a high superheat, that accompanied with your normal - high subcooling makes me think you are correct that the txv is bad. Are you sure it's a txv and not a piston and is it a heat pump

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  10. #8
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    Sounds like a bad TXV...

    I have one of those to change today... did not have the correct valve with me yesterday.

    The more R22 added... the higher the head and SC... however the suction pressure and SH did not change.
    Note: New LL dryer inside just before the TXV.
    Ga-HVAC-tech

    Your comfort, Your way, Everyday!

  11. #9
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    If a customer calls and says OD unit not running....... I still go to the air handler first thing.... even those customers who "know" its a cap or contactor.

    Might as well see what you are working with.... check the evap... blower...... aux drain pan could be sitting there full of water ...... run the leak detector around in the evaporator.... Once the AH has been looked at...... is it piston or txv..... take a few pics in case this turns into a changeout....

    Then go to the condenser........ If its a cap or contactor...... I still throw the gauges on it too..... Customer can whine a little bit about the additional time..... but I would rather see the complete picture than run in and throw a cap on and leave...... only to be called back a week or month later.
    The bible is my constitution and the constitution is my bible.

    WE THE PEOPLE refers to THEM and not YOU.

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  12. #10
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    Quote Originally Posted by martyinlincoln View Post
    Regularly to a customer might mean once a year.
    I see a lot of folks with electronic air cleaners etc....... who were told by the installers that they only need to be cleaned once a year.... dang prefilters will look like rugs...... and you try to educate them on proper procedures and then they throw the old.... well why did so and so tell me once a year...... like they dont believe you....... lol

    Those 3 month filters the same way....... why do they sell them for 90s days if they dont last that long...... or the old paul harvey electrostatic ones...... I tell the customer they are known as unit killers...... but they insist on keeping them......

    Filters in the supplys..... lol.... Ive been on two of them recently..... Im trying to help these ignorant jack a**es....... and they have more trust in the person that sold them that junk......

    Take em out.... tell the customer they will kill their unit.... and I bet they put them back in as soon as I leave........ lol
    The bible is my constitution and the constitution is my bible.

    WE THE PEOPLE refers to THEM and not YOU.

    Chewbacca Mom 2016

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  14. #11
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    Quote Originally Posted by corny View Post
    I see a lot of folks with electronic air cleaners etc....... who were told by the installers that they only need to be cleaned once a year.... dang prefilters will look like rugs...... and you try to educate them on proper procedures and then they throw the old.... well why did so and so tell me once a year...... like they dont believe you....... lol

    Those 3 month filters the same way....... why do they sell them for 90s days if they dont last that long...... or the old paul harvey electrostatic ones...... I tell the customer they are known as unit killers...... but they insist on keeping them......

    Filters in the supplys..... lol.... Ive been on two of them recently..... Im trying to help these ignorant jack a**es....... and they have more trust in the person that sold them that junk......

    Take em out.... tell the customer they will kill their unit.... and I bet they put them back in as soon as I leave........ lol
    if it's accessible, I try to install a 4.5" media filter on all of my installs, the filter and rack combined only range from 60-90 bucks, depending on size. That way if the only time the filter gets replaced is at the annual tune up, at least the pleats are deep enough to allow some air flow still.

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  16. #12
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    Quote Originally Posted by jad051088 View Post
    If there was an airflow problem you would have a low superheat but you don't, you have a high superheat, that accompanied with your normal - high subcooling makes me think you are correct that the txv is bad. Are you sure it's a txv and not a piston and is it a heat pump

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    Yeah I visually verified that it had a TXV. Why would low airflow cause a low superheat?


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  17. #13
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    Thread Starter
    Quote Originally Posted by corny View Post
    I see a lot of folks with electronic air cleaners etc....... who were told by the installers that they only need to be cleaned once a year.... dang prefilters will look like rugs...... and you try to educate them on proper procedures and then they throw the old.... well why did so and so tell me once a year...... like they dont believe you....... lol

    Those 3 month filters the same way....... why do they sell them for 90s days if they dont last that long...... or the old paul harvey electrostatic ones...... I tell the customer they are known as unit killers...... but they insist on keeping them......

    Filters in the supplys..... lol.... Ive been on two of them recently..... Im trying to help these ignorant jack a**es....... and they have more trust in the person that sold them that junk......

    Take em out.... tell the customer they will kill their unit.... and I bet they put them back in as soon as I leave........ lol
    I've seen a few people with filters in the supplies. I tell them that would restrict airflow, but is it really that bad to have them?


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