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Thread: Nest (3rd Gen) thermostat gives error code E104

  1. #7
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    Quote Originally Posted by Thermostat View Post
    All of the other wires that connect from the Nest to the ECW will stay as there were. Only the G wire changes. The C terminal on the ECW will now have 2 wires.
    I received the PAM-1 relay (from Amazon) and tried to understand the corresponding wiring (colors) for correct connections... Here's what I'm thinking:

    Pam-1 white / 0V > C terminal on NCM-300
    Pam-1 red / 24V > G terminal on NCM-300
    Pam-1 black / 120V > R terminal on NCM-300




    Pam-1 blue / C > G wire from Nest thermostat.
    Pam-1 orange / N.O > What does this connect to?
    Pam-1 yellow / N.C > What does this connect to?

    Please correct me if I'm wrong.... Appreciate any/every help!

    Thank you

  2. #8
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    Pam-1 white / 0V > C terminal on NCM-300
    Pam-1 red / 24V > G terminal from Nest
    Pam-1 black / 120V > Place a wire nut on this wire

    Pam-1 blue / C > R terminal on NCM-300
    Pam-1 orange / N.O > G terminal on NCM-300
    Pam-1 yellow / N.C > Place a wire nut on this wire

  3. #9
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    Quote Originally Posted by Thermostat View Post
    Pam-1 white / 0V > C terminal on NCM-300
    Pam-1 red / 24V > G terminal from Nest
    Pam-1 black / 120V > Place a wire nut on this wire

    Pam-1 blue / C > R terminal on NCM-300
    Pam-1 orange / N.O > G terminal on NCM-300
    Pam-1 yellow / N.C > Place a wire nut on this wire
    Great, I wired it up last night and it didn't make any difference... After making the above suggested connections via the PAM-1 relay, these are the connections that went to the "thermostat zone-2" on NCM-300:

    1. White (from PAM-1 relay) & Blue wire (common from Nest thermostat) ----> C on NCM-300
    2. White wire (from Nest thermostat) ----> W/E on NCM-300
    3. Yellow wire (from Nest thermostat) ----> Y on NCM-300
    4. Blue (from PAM-1 relay) & Red wire (from Nest thermostat) ----> R on NCM-300
    5. Orange (from PAM-1 relay) ----> G on NCM-300

    I still think I might've wired it somewhat incorrectly and the reason is (1) & (4) from above.. Does that sound right to you?

    Looking at the "Equipment" info on my Nest, it seemed to read the wires incorrectly... Please see below:

    Instead of: Y1-G-Rc-W1-C
    It read as: Y1-C-G-W1-Rc (I think, can double check & get back to you again)

    Any idea what's going on? This is the first time I'm having so much trouble with a Nest thermostat.. The Zone-1 Nest works perfectly, NOT sure what's going on with Zone-2....

    Thank you for the help. Appreciate your time!
    Last edited by maxie.maverick; 06-18-2018 at 09:25 AM.

  4. #10
    Administrator

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    If you have everything wired correctly the Nest my have a internal issue with the G circuit.

  5. #11
    Junior Member

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    Quote Originally Posted by Thermostat View Post
    If you have everything wired correctly the Nest my have a internal issue with the G circuit.
    I tried swapping my Nests around and got the same error.. Then I switched the base and still got the same error.

    Something is very weird with the G-wire.

  6. #12
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    Assume your G wire is green. Should see if it is a wire issue or a Nest issue since the relay ruled out an NMC-300 issue.
    Swap the yellow and green wires at both ends. If the error changes then it is a wire issue.
    Next try leaving green disconnected at the zone controller and see what Nest error you get. Some zone boards will work without a G by turning it on whenever it sees Y. Otherwise connect Yellow to both Y and G at the NCM-300.
    Lastly, try disconnecting G at the Nest.

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