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  1. #53
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    Jul 2009
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    South Carolina
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    I've watched the video & have a question to all those who think its a pressure switch causing the short cycling. How can that be when the board should have a delay on break built in? On an LP or HP trip shouldn't there be a longer delay?
    Gary
    -----------
    http://www.oceanhvac.com
    An engineer designs what he would never work on.
    A technician works on what he would never design.

  2. #54
    Join Date
    Jul 2002
    Location
    Yuma, AZ
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    Quote Originally Posted by garyed View Post
    ...How can that be when the board should have a delay on break built in? On an LP or HP trip shouldn't there be a longer delay?
    That depends on the wiring and the logic of the controls. There is a time delay in the circuit but the TDR relay cycles sump heat off during compressor operation and delays energizing the sump heat for 30 mins after Y call is removed.
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

  3. #55
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    Quote Originally Posted by lynn comstock View Post
    That depends on the wiring and the logic of the controls. There is a time delay in the circuit but the TDR relay cycles sump heat off during compressor operation and delays energizing the sump heat for 30 mins after Y call is removed.
    I have no idea what sump heat is but I don't know of any modern unit made today that will short cycle like that on low or high pressure. Usually if there's a pressure switch for protection there's also a protection from short cycling from the pressure switch.
    In the old days it was common to see short cycling like that but not in this circuit board age of today. I'm not familiar with this particular unit so you may be correct but I have a hard time believing Trane's design would be that far behind the times.
    Gary
    -----------
    http://www.oceanhvac.com
    An engineer designs what he would never work on.
    A technician works on what he would never design.

  4. #56
    Join Date
    Jul 2002
    Location
    Yuma, AZ
    Posts
    2,361
    The logic of the stat and the defrost board are not shown in the wiring diagram:4TWR5048-SF-1C.pdf
    The motor starter is obviously stopping and starting both the compressor and fan. The only controls in the MS circuit that can do that are the LPCO and the HPCO and the K relay (K3 on the defrost board). The pattern is too regular not to be pressure related. The stat or the defrost board may have a malfunctioning time delay. The primary issue, though, is what control is causing the cycling? The time delay issue is secondary but not insignificant.
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

  5. #57
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    Jul 2009
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    South Carolina
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    Quote Originally Posted by lynn comstock View Post
    The logic of the stat and the defrost board are not shown in the wiring diagram:4TWR5048-SF-1C.pdf
    The motor starter is obviously stopping and starting both the compressor and fan. The only controls in the MS circuit that can do that are the LPCO and the HPCO and the K relay (K3 on the defrost board). The pattern is too regular not to be pressure related. The stat or the defrost board may have a malfunctioning time delay. The primary issue, though, is what control is causing the cycling? The time delay issue is secondary but not insignificant.
    I looked at the diagram & now I see what you're talking about.
    I think whoever designed that control system needs to go back to school or learn to draw a better diagram. Unless I'm missing something it looks like you're absolutely right. All the pressure controls are downstream of the board & there is no short cycle protection from them. At least I didn't see any TD other than the one that breaks high voltage to the heater that they could effect. So there's nothing to stop that compressor from short cycling on high or low pressure until it cuts out on overload indefinitly. That's insane.
    Gary
    -----------
    http://www.oceanhvac.com
    An engineer designs what he would never work on.
    A technician works on what he would never design.

  6. #58
    Join Date
    Nov 2006
    Location
    Southeastern Pa
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    18,322
    Quote Originally Posted by garyed View Post
    I have no idea what sump heat is...
    It's another name for crankcase heat.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  7. #59
    Join Date
    Aug 2011
    Posts
    19
    OK, latest update...

    The repair guy just left. So far, this guy spent the most time here trying to figure things out.

    1. He said that the freon was low and brought the pressure back up, contradicting the last guy.
    2. He said the control wire was wired wrong. Something about two wires being connected when the instructions from Trane clearly say that only one of them should be going to the outside unit.
    3. He also replaced the thermostat because he said it did something it wasn't suppose to do when he adjusted the temperature.
    4. He put a starter kit on the outside unit, and didn't know why one wasn't already on there because he said it was standard with new installs.
    5. He couldn't explain why the unit was short cycling, but his guess was that it was a low pressure fault and not a high pressure--but also said it could have something to do with the control wire not being wired correctly, but ALSO said it could be caused by the air flow, and said I should change the filter--and would have to do so more often since my single air intake is on the floor and is more likely to get dirtier faster.

    So, that's what he did. We'll see if it happens again...

    He said if they have to come out again they'll be bringing a Trane rep with them to try and figure it out--and straight up admitted that the unit is brand new and a lot of guys are not familiar with them yet, since they came out this year. I appreciated his honesty.

    Fingers crossed!

  8. #60
    Join Date
    Jul 2002
    Location
    Yuma, AZ
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    Quote Originally Posted by phatmass View Post
    ... I appreciated his honesty...
    Me, too.
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

  9. #61
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    Aug 2011
    Location
    Ontario
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    381
    Stay tuned, this one ain't over yet !!!!!!

  10. #62
    Join Date
    Aug 2011
    Posts
    19
    Three days with no short cycling!!!

    I'm optimistically hopeful that the last guy fixed it.

    He did four things:
    1. increase pressure
    2. fixed control wire since it was wired wrong per Trane instructions
    3. replaced thermostat
    4. installed starter kit

    So, I don't know WHICH one of those things fixed it, but it appears that one of them did.

    Also, the air out of the vents seems to be a lot colder now--don't know what that can be attributed to.

  11. #63
    Join Date
    Mar 2011
    Location
    VIRGINIA
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    37
    Good for him... I hope everytjing was took care and now you are enjoying your comfort. But I am wondering when they will come back...?

  12. #64
    Join Date
    Nov 2005
    Location
    Milwaukee, WI
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    279
    Quote Originally Posted by phatmass View Post
    4. He put a starter kit on the outside unit, and didn't know why one wasn't already on there because he said it was standard with new installs.
    Ummmmm

    Hard Start Kit ?

    I'm assuming here but I have never known of a unit needing a Hard Start Kit from the Factory, the Hard Start kit is just that " HARD to Start "

    If I was you I'd double check what start kit he put on, I have had to put a hard start kit oddly enough on two armstrongs ( they have very fine coils ) that took some abuse because the coils were never cleaned in 2 years and there are cotton wood trees in my neighborhood.

    After cleaning them they just didn't start even tho I had power and a good capacitor, I then needed to install a " Hard Start Kit " because the start/run winding internally on the compressor were " Hurt " as I call it.....

    If I had a warranty and there was no negligence on plugged coils and my unit needs a hard start kit already I'd want a new compressor or heck a new outside unit all together !!!

    Just my 0.02
    I forgot my Pen !!!

    Quote Originally Posted by RoBoTeq View Post
    Think of the old stuff as dumb and strong and the new stuff as smart but just not so tough.

  13. #65
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    Nov 2006
    Location
    Southeastern Pa
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    In the olden days (25 years ago) it was common to see a hard start kit as part of the OE design. It was just a "starting circuit." Now, when they get added later, we call it "hard start" or "start assist," but it used to be just another set of components.

    Maybe the owner of the Co is a guy my age and puts them in routinely, because they are left out of the OE design.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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