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  1. #14
    Join Date
    Feb 2006
    Location
    USA
    Posts
    4,381
    hvacpope in all my years & 100's n 100's L series units I found 1 defective A55 ... it was M1-5 .. I've encountered many misdiagnosed controllers tho lol

  2. #15
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    18,548
    Quote Originally Posted by hvac wiz 79 View Post
    hvacpope in all my years & 100's n 100's L series units I found 1 defective A55 ... it was M1-5 .. I've encountered many misdiagnosed controllers tho lol

    I've replaced one that I knew was bad.

    AND....one that Lennox tech support SAID was bad.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  3. #16
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    18,548
    Quote Originally Posted by mturan View Post
    Yea I jumped the switch at the A57 input cause its on circuit #2 and still got the diagnostic so i eliminated the switch and the wires. I have also changed out the A55 and A57 boards on this. Not sure what the IMC is but i can look into the ecto settings and try and do something there. I just appreciate the dialogue on this as I'm not that familiar with the lennox unit. Thanks everybody.
    IMC is a name for the A55. If you have already replaced it and you still have the problem, hang onto the old board. You may want to put it back after a closer look.

    Wish I could be there to look at it, but all we can do is follow your reporting.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

    AOP Forum Rules:







  4. #17
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    18,548
    Let's assume for a moment that you are still having the same problem as before.

    Now, step back and look at this like it has just been found. Look at the codes. Use the "recall" switch setting and write them down, then clear them by holding in the black button till you see "0." Then, move the recall switch back to its normal position.

    If there is another similar unit nearby, make sure all the DIP switches on the board are set up correctly, such as phase, gas, etc.

    Look at all the terminal strip jacks and plugs. Is everything mated together evenly?

    Does the switch mentioned in the code agree with the switch designation of the stage where you have your guages?

    I would get my meter on the low pressure circuit and monitor the voltage while observing the low pressure while the unit runs, and look for the switch to open. If that switch never opens and you get a code, and you are using a new board, I would go back over the connections and wiring again.

    Another test I would do is to disconnect the switch at its harness while the unit runs, and confirm that the board will respond to the opening of that circuit with the same code.

    Let us know what you find.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

    AOP Forum Rules:







  5. #18
    Join Date
    Jul 2011
    Location
    Montana
    Posts
    6
    Great Info on this unit. I like the recall information as i didn't know about that. I will get back to this unit eventually as it is quite a distance from where I live. I will be back there eventually though. Thanks again for all the help.

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