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    cdehrlich's Avatar
    cdehrlich Posts: 5, Reputation: 1
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    #1

    Aug 7, 2007, 08:14 AM
    AC runs continuously with fan in ON position
    When I put my electronic thermostat to the FAN position, the AC runs continuously (even if I have the HEAT/COOL switch OFF!).

    I have checked the wiring on the thermostat and on the furnace control connections -- it all seems to be correct. Could it be a faulty thermostat?
    acetc's Avatar
    acetc Posts: 1,004, Reputation: 79
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    #2

    Aug 7, 2007, 08:33 AM
    It could be that the control wire for the fan "G" is shorted or touching the cooling wire "Y" either in the back of the thermostat or at the furnace or in attic.
    cdehrlich's Avatar
    cdehrlich Posts: 5, Reputation: 1
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    #3

    Aug 7, 2007, 08:47 AM
    Quote Originally Posted by acetc
    It could be that the control wire for the fan "G" is shorted or touching the cooling wire "Y" either in the back of the thermostat or at the furnace or in attic.

    OK -- thanks. I will check that more closely.
    acetc's Avatar
    acetc Posts: 1,004, Reputation: 79
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    #4

    Aug 7, 2007, 08:59 AM
    My guess is that it is probably not your thermostat.
    J Costa's Avatar
    J Costa Posts: 88, Reputation: 9
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    #5

    Aug 7, 2007, 03:39 PM
    Quote Originally Posted by cdehrlich
    When I put my electronic thermostat to the FAN position, the AC runs continuously (even if I have the HEAT/COOL switch OFF!).

    I have checked the wiring on the thermostat and on the furnace control connections -- it all seems to be correct. Could it be a faulty thermostat?
    If you have your fan in the in the on position and not auto your a/c will run all the time.
    cdehrlich's Avatar
    cdehrlich Posts: 5, Reputation: 1
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    #6

    Aug 8, 2007, 05:47 AM
    Quote Originally Posted by acetc
    My guess is that it is probably not your thermostat.
    I checked and you are correct -- it is not the themostat (I had an old one I hooked up). Also, no wires shorted together. Any other suggestions?
    cdehrlich's Avatar
    cdehrlich Posts: 5, Reputation: 1
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    #7

    Aug 8, 2007, 05:51 AM
    Quote Originally Posted by J Costa
    If you have your fan in the in the on position and not auto your a/c will run all the time.
    Unless I am mistaken, when the switch is in the FAN position, the FAN should run all of the time and the AC compressor should still only run when cooling is called for.
    acetc's Avatar
    acetc Posts: 1,004, Reputation: 79
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    #8

    Aug 8, 2007, 04:37 PM
    Cdehrlich, you are correct the a/c will cycle and the fan will run continuously, if the a/c runs continuously then try disconnecting the two thermostat wires going to the outdoor unit , if it still runs then the contacts in the outdoor unit might be stuck together (this happens) Turn off power when trying to fix contactor.
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