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Thread: Nest Wiring issue when using heat

  1. #1
    Junior Member

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    Question Nest Wiring issue when using heat

    Hello all,

    I have a 2nd gen Nest Thermostat with a RUUD A/C. When I initially installed the Nest (2014) I went through an issue where I would turn on the heat but no hot air would blow. I used Nest Forums and a helpful 'hvactech' guided me through and found out that since I had RUUD that I needed to switch my O/B wire to operate as "B" within the Nest -- and this fixed it then.

    This is a picture of my wiring setup in the winter of 2014 using this RUUD system.

    In the summer of 2015 my Nest backplate went out and I had to RMA and rewire and set the O/B back to "B". But I never tested the heat, dummy me.

    Now my A/C cooling works but the heat kicks on for a second then turns off with no hot air. I've tried switching the RED Rh wire over to the Rc terminal (based on a picture I took previously) but no luck.

    I'm obviously not an electrician. Can anyone help me out?

    Thanks for any info

  2. #2

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    You could run a test by turning the power off to your HVAC system and remove the red, yellow and green wires from the thermostat and join them together. This should run the system in heat when you turn the power back on. If the system does run in heat it would indicate that the issue is with the nest thermostat. If you do run this test make sure that none of the wire touch the C wire when the HVAC system has power.

  3. #3
    Junior Member

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    Woof, I'll have to think about this. I get nervous when touching wires together -- mainly for accidentally blowing up equipment. :-)

    Thanks for the advice!

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