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-   -   Fan switch turns on AC blower, not the fan (https://www.askmehelpdesk.com/showthread.php?t=462094)

  • Apr 2, 2010, 05:41 PM
    cdc_carter
    Fan switch turns on AC blower, not the fan
    I just moved into a new house and the digital thermostat is not working as I expect.

    When I turn the heat/cool swith to "off" and the fan switch to "on", the blower on the central air unit outside kicks on, but the fan in the inside unit does not.

    When I turn the heat/cool switch to "cool" and the fan switch to "on", both the blower and the central air unit kick on.

    I assume it is wired incorrectly, but before I pull the cover and start messing with wires, I want to see if my assumption seems correct or if there are watch-outs I need to be aware of.

    Thanks
  • Apr 2, 2010, 05:46 PM
    Joshdta

    Sounds like the wires are backwards. G and y probably.
  • Apr 2, 2010, 05:51 PM
    cdc_carter

    The fan also kicks on when the furnace runs. Would that still be the case if g and y are backwards, or would I be seeing the outside AC unit kick on when the furnace runs?
  • Apr 2, 2010, 06:02 PM
    Joshdta

    Does it come on as soon as you turn it to heat? Or after a breef time? Also if you turn everything to off and the fan to auto will it shut off?
  • Apr 2, 2010, 06:16 PM
    cdc_carter

    I think that you are correct, that the wires are backwards. If I turn it to heat and fan to on, the AC blower kicks on. I have to turn the fan mode to auto for it to kick on in furnace mode and it does so immediately.
  • Apr 2, 2010, 06:18 PM
    Joshdta

    What brand furnace do you have and is it gas, or electric heat?
  • Apr 2, 2010, 06:47 PM
    cdc_carter

    A gas Trane
  • Apr 2, 2010, 07:18 PM
    Joshdta

    Turn off the power at the furnace, take the t-stat off the wall and let me know what wire is where?
  • Apr 2, 2010, 08:31 PM
    KISS

    Figures.

    With conventional heat, the furnace controls the fan in heat mode.

    In cool, the thermostat controls the fan. (g and y energised at the same time)

    Fan energises G.

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