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  1. #1
    Join Date
    Nov 2010
    Location
    Virginia
    Posts
    8

    Trane RTU Tripping Transformer CB

    Have an issue w/ a 7.5 Trane RTU that smoked it's 24 volt transformer. Replaced transformer w/ one that has a circuit breaker. Tripped out as soon as power is applied. Traced back to wire # 172A connected to the Reliatel board, disconnected that wire, and the transformer does not trip. At least I have some air movement now and perhaps some electric heat. This wire 172A goes thru pressure switches before it gets to the board, but they seem to be OK. Any ideas or help would greatly be appreciated.

  2. #2
    Join Date
    Jul 2007
    Location
    Mount Airy, MD
    Posts
    7,281
    Moved thread over to the commercial section of site for a better response

  3. #3
    Join Date
    Feb 2010
    Location
    MEXICO
    Posts
    472
    reviews the core of the contactor / or compressors, if not bond well or vibrate increases current consumption and protects the transformer

  4. #4
    Join Date
    Mar 2008
    Location
    Central NH
    Posts
    141

    bust out the ohmmeter

    Lock one lead under the ground clamp and start tracing back through from the transformer until you no longer get a reading to ground. At that point you have located your issue and can fix it. My guess is a wire has chaffed trough and is contacting the chassis of the unit.

  5. #5
    Join Date
    Mar 2010
    Location
    Va.
    Posts
    180
    Can you post the model/serial no's. Sounds like your on the right track. The high pressure switch circuit ends at the compressor contactor coil. Try removing the coil wire and see what happens.

  6. #6
    Join Date
    Nov 2010
    Location
    Virginia
    Posts
    8
    Thanks Everyone, Trane mod# WSC072A3RKAOWH ser# 308101165L
    Will not get back there til next week for further analyses, but I will try everything ya'll have recommended. Gosh, I didn't even think the compressor itself could have an issue; should have checked that before I left as well.
    Thanks again everyone and Have a Wonderful Thanksgiving !!

  7. #7
    Join Date
    Nov 2010
    Location
    Virginia
    Posts
    8
    Thank you !!

  8. #8
    Join Date
    Feb 2008
    Location
    canton, ohio
    Posts
    26

    dean59

    try this,disconnect the 24v at the econimizer board or disconnect it completly,i have found shorted board a few times,also check the stat wiring
    at the control panel door,i have found a couple of shorted wires here.were the vibration from the unit rubbed through the stat wire insulation and was
    triping the 24v transformer reset button.
    hope this helps

  9. #9
    Join Date
    Nov 2010
    Location
    Virginia
    Posts
    8
    Thanks Dean,

    Will try when I get back there on the 15'th. With the 172A wire (coming from HPS & LPS) disconnected from the Reliatel board, they have auxillary heat for now and are perfectly content til my next monthly visit.
    Will try what you recommend, and fill everyone in by the 17'th on my findings.

    Thanks Again to All and Happy Holidays !!!

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