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  1. #1
    Join Date
    May 2016
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    Lennox RTU Condenser fan is not running in stage 1 cooling.

    I am Having an issue with a Lennox RTU M/N:LGH036H4ES1Y S/N:5610C03692.

    The Condenser fan does not come on in stage 1 cooling so the unit trips out on high head pressure. The fan does kick on in stage 2 cooling. I tested the voltage when calling for stage 1 and it is all there. When i run stage 2 i have the same voltage but the fan will actually run. I cannot figure out what is holding that fan out in stage 1. i swapped the wires for stage 1 and 2 for now. So when i give the signal for stage 1 stage 2 kicks on so the fan runs. then if there is a need for a second stage my controls send the signal for stage 2 then stage 1 will kick on so the fan will stay running.

    has anyone seen this issue

  2. #2
    Join Date
    Mar 2015
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    you say there is voltage on first stage. did you check each leg to ground?

  3. #3
    Join Date
    May 2016
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    Thread Starter
    Yup and the voltage is all there I'm literally scratching my head on this one the only thing I can think of is that it is an issue with the board

  4. #4
    Join Date
    Jan 2012
    Location
    Missouri, USA
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    Do the fans lead/lag?

  5. #5
    Join Date
    Mar 2015
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    Are the fans three phase?

    Sent from my SM-G900V using Tapatalk

  6. #6
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    May 2016
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    Thread Starter
    No...and there is just one fan and one compressor

  7. #7
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    May 2016
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    Thread Starter
    One phase I believe

  8. #8
    Join Date
    May 2006
    Location
    Austin, Texas
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    If you are not sure if it is single phase, you may need to call a more experienced tech to check voltage at motor.

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  10. #9
    Join Date
    Aug 2002
    Location
    Southold, NY
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    Quote Originally Posted by dfj92 View Post
    One phase I believe
    O
    M
    G

  11. #10
    Join Date
    Mar 2015
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    I briefly read the service manual. It's a PSC motor. I would recheck it and make sure you truly have voltage going to the motor.

    Sent from my SM-G900V using Tapatalk

  12. #11
    Join Date
    May 2016
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    Thread Starter
    I had my co-worker check too we are both getting the same thing. It is a 0-10v signal and when cooling is off we are getting 0v and when stage 1 is on I get the 10v signal but it won't turn on. I get the same reading when stage 2 is on but the fan actually runs

  13. #12
    Join Date
    Feb 2013
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    north georiga
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    check voltage leg to leg
    if corny was a part on a washing machine,,, he'd be the agitator

    “Those who CAST the votes decide nothing; those who COUNT the votes decide everything.” – Stalin even evil men say things worth paying attention to

    A Nation of Sheep - Breeds a Government of Wolves

    Gangster Al Capone once remarked that anyone who can walk to the welfare office can walk to work.

  14. #13
    Join Date
    May 2016
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    Thread Starter
    my co worker did that and said its all there were getting the 210 for power and 10v when either stage is on...im just an apprentice so im still learning. my co worker is the more experienced one and he checked everything. he even spent over an hour with tech support at lennox and they could not figure it out.

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