Not getting 24v from transformer secondary at control board

Discussion in 'HVAC' started by Bdog, Sep 16, 2018.

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  1. Sep 21, 2018 #21

    bud16415

    bud16415

    bud16415

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    Sometimes truth is stranger than fiction.


    Start at the breaker and work down the line checking voltage. Somewhere along the line you will find a bad connection. Start with tightening the screws on the breaker. Over the last two months I have found twice a loose connection at the panel solved the problem.
     
  2. Sep 22, 2018 #22

    Bdog

    Bdog

    Bdog

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    That gets me a little nervous, opening up the breaker panel and poking around with a screwdriver. Finding the hot on that breaker isn't an issue but since all the commons tie into a master common track I'm not sure if I can identify the right one. Any advice?
     
  3. Sep 22, 2018 #23

    Bdog

    Bdog

    Bdog

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    Went ahead and checked tightness at the breaker. No issues. The furnace is the only thing on that breaker so I'll check the voltage at the J box switch in the attic next.
     
  4. Sep 24, 2018 #24

    Bdog

    Bdog

    Bdog

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    Well, well well. Thanks to Bud16415 I went once again in search of the source of lower voltage and found perfect 120v at the breaker box, then went into the attic Junction box sending power into the unit and found that the positive wire had slipped out of the back of the light switch in that box. It was still in far enough to look normal to all of us who inspected it until I took the switch out. it was still close enough to a proper connection that it was pulling the 100-108v, but this was not enough for the transformer. Simple loose wire that took a week and $400 of unnecessary expense. My mistake. Live and learn.
     
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  5. Sep 24, 2018 #25

    maxdad118

    maxdad118

    maxdad118

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    Glad you got it resolved!
     
  6. Sep 24, 2018 #26

    bud16415

    bud16415

    bud16415

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    Glad we could help.


    I have found in years of troubleshooting sometimes all you need is to explain a problem and have someone on the other side listen and make general comments. Forums are great to keep you focused and to not give up.


    The second key to troubleshooting is when something changes or is out of place and take that as a clue. In this case it was the 108V.


    Don’t be a stranger to the forum. Nice bunch of folks here and its ok to hang out when everything is working good.
    :D
     

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