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Thread: Nest 3rd Gen install on a Carrier System

  1. #1
    Junior Member

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    Nest 3rd Gen install on a Carrier System

    Hello all,



    I am trying to get a Nest thermostat installed on a Carrier Two stage cooling and one stage heat pump. The wires from the previous thermostat and where I believe they go are as follows:

    Terminal Wire color Nest terminal
    G. Green. G
    Y2. Yellow. Y1
    R. Red. Rh
    C. Blue x2 C
    O/W2. Orange. O/B
    Hum. Red. *
    Dehum. Gray. ----
    S1. Yellow. ----
    S2. White. ----
    W1. White. W1

    Currently I am having trouble getting the heat to work. The fan comes on but blows unheated air. So I guess I'm sure about the G and C wires. I am unsure about Rh over Rc; I'm not sure it makes a difference. I also am unsure about leaving the S1 & S2 unconnected. I currently believe them to be temperatures from the outdoor unit but that may be incorrect.

    If anyone has any insight, I would be more than interested. Thanks so much.

    -jamcshan

  2. #2
    Administrator

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    Can you clarify how many stages of cooling that you have? Two stage cooling with one stage heat pump is not typical. How many compressors outside do you have. Was there a Y or Y1 wire on the existing thermostat? Connecting R to Rh on the Nest is what Nest recommends. If S1 and S2 are connected to a outdoor sensor they can be taped off and not used.

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