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  1. #1
    Join Date
    Jan 2019
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    Trane XL16i defrost problem ongoing

    Hi
    I have a 2016 XL16i, the unit is working great in AC mode, but as soon as it switches to heat mode, it will frost up and now it s completely shut down.
    The defrost board was replaced twice last year (one DOA) and pressures were checked.
    It looks to me the defrost cycle is too short and the heat pump is not able to completely get rid of ice. now it s 5 degrees f. outside. running in aux heat right now.
    see attached pictures

    any suggestions to permanently fix this issue?
    Attached Images Attached Images    

  2. #2
    Join Date
    Aug 2002
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    Southold, NY
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    Thats a refrigerant flow issue

    Pressures are fine means nothing. Get the installing contractor back!

  3. #3
    Join Date
    Jan 2014
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    New England
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    The install guide ( readily available ) says if checking/charging in winter mode ( below 55 degree OD temperature) to use the superheat method, the install guide gives all the information for the Contractor to follow and adjust. Says the indoor temperature to be between a certain range.

    The install guide says the final adjustment charge is to be done in cool mode, again the OD and ID temperature to be a certain temperature range and follow the sub cooling guide.

    I would start there first. Relying on only pressure reading is not the correct method.

    Would need to start with a clean frost free OD coil for starters.

    Has it been like this for 2+ years?

    Your system they installed is a AHRI match also and got registered?

  4. #4
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    Jan 2019
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    Thread Starter
    yes, it s recurring since the installation, last year the contractor replaced the defrost board saying it was defective.
    If I manually trigger a defrost cycle by shorting pins on board, can I damage something in the current state ? Although I don t know if this will work since the unit is not responding when I enter test mode with the ecobee thermostat.

  5. #5
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    Jan 2019
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    Thread Starter
    Just called the contractor, they are contacting Trane and will get back to me...

  6. #6
    Join Date
    Jan 2014
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    New England
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    Quote Originally Posted by discoboy1 View Post
    Just called the contractor, they are contacting Trane and will get back to me...
    It's nice that they are calling Trane Technical Support, the install guide also gives specific instructions on checking/adjusting charge in winter mode if it's a charge issue. Between the two they should be able to resolve your problem.

    Let us know what they find/did, hopefully they did not charge you for those defrost boards as they should be covered under the manufacturer warranty, and the labor warranty covered up until that expires/expired.

    You may want to remind them that Trane wants the final adjustment charge to be done in cool mode ( says that in the install guide ) Dated as of 2014 for the XL16i

    Note: It is important to return in the spring or summer to accurately charge the system in the cooling mode when outdoor ambient temperature is above 55 F.

    They should not have to much trouble to simulate a defrost ( via OD unit ) to remove the ice accumulation on OD unit before doing any type of check, if it's only the charge issue that's causing those bands.
    Last edited by Bazooka Joey; 01-14-2019 at 02:56 PM.

  7. #7
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    Jan 2019
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    Thread Starter
    I got news from contractor, 1-2 weeks delivery for defrost board, although they have other points they need to check according to Trane.

    To further document the issue, I took the panels off, and can see 4 blinks of the red light (suction temperature sensor out of range according to the document I have)
    I could not find the jumpers for the termination temperature on my model of defrost card. (set to 47f or 70f)
    Here are more pictures
    Attached Images Attached Images       

  8. #8
    Join Date
    Jan 2014
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    New England
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    Not to be confused with the TXV sensing bulb, parts should be under warranty.

    That's why I like time/temperature defrost systems, simpler to troubleshoot IMO.

    I always kind of thought that if you carry the big recognized brands like Carrier, Trane as an example that they makes you go to some basic classes on the more complicated systems, so the Installing Contractor can knock out pretty much a call back the first time...and not make them or Trane look bad.

  9. #9
    Join Date
    Aug 2009
    Location
    Beatrice, NE
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    There is a problem with the way the refrigerant is being fed to the coil. In general this means either the TXV is bad or the charge is off. I would lean towards the charge. As has been said i wonder if the inside unit is a proper match. If it is not a proper match then it can cause charge issues from heat to cool or vise-a-versa.

  10. #10
    Join Date
    Feb 2006
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    Phoenix,AZ
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    Do they (heat pumps) even work when it's only 5°F outside?

  11. #11
    Join Date
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    Quote Originally Posted by KB Cool View Post
    Do they (heat pumps) even work when it's only 5°F outside?
    Many produce heat when its -15°F outside.
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    How many times must one fix something before it is fixed?

  12. #12
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    Feb 2006
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    Quote Originally Posted by beenthere View Post
    Many produce heat when its -15°F outside.
    Yeah, if your return temp is 60° and your supply is 63°. I guess you could say it's producing heat!

  13. #13
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    Quote Originally Posted by KB Cool View Post
    Yeah, if your return temp is 60° and your supply is 63°. I guess you could say it's producing heat!
    More like return temp is 70 and supply is 78.

    Which on a 3 ton, would be about 10,368 BTUs, for about 80% of the cost of that same amount of heat with electric resistance heat.
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