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  1. #27
    Join Date
    Dec 2002
    Location
    SouthEast NC ICW & Piedmont Foothills
    Posts
    7,927
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    Heating, Units Without Economizer 04A--07A (single compressor model): When the thermostat calls for heating, terminal W1 is energized. DFB receives this input at P27. The DFB removes the output at P37 (RVS1) reversing valve solenoid is de--energized and reversing valve moves to Heating position. DFB issues outputs at P39 (IFO), OF, and P310 (COMP1). The indoor fan motor or contactor (IFC) is energized; indoor fan motor starts. Outdoor fan relay OFR is energized; outdoor fan motor runs. Compressor contactor C1 is energized; refrigeration circuit operates in Heating mode.

    this is from a 2009 service manual. Uncertain of actual serial # of unit in discussion. The way this sequence was described to me is; that control board is looking for what signal is NOT there when determining heat call, mainly the "Y" signal. Can't located the really old IOM that contained the T-stat set up.
    It`s better to be silent and thought the fool; than speak and remove all doubt.

  2. #28
    Join Date
    Jan 2010
    Posts
    19,281
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    Quote Originally Posted by Cool breeze 38 View Post
    anyone in here know how to read that wire diagram posted previously?


    Can anyone that have made comments on operation show. how on the wire diagram that their theory is right.
    .
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  3. #29
    Join Date
    May 2018
    Location
    VA/DC
    Posts
    320
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    that right. why would you need to configure the thermostat for electric heat?
    And why would the unit run in cooling if only w1 is energized. I'm referencing your previous comment


    VTP99 that pic doesn't show what the HR is doing on a call for w1. that's just the defrost cycle.


    Quote Originally Posted by dandyme View Post
    Heating, Units Without Economizer 04A--07A (single compressor model): When the thermostat calls for heating, terminal W1 is energized. DFB receives this input at P27. The DFB removes the output at P37 (RVS1) reversing valve solenoid is de--energized and reversing valve moves to Heating position. DFB issues outputs at P39 (IFO), OF, and P310 (COMP1). The indoor fan motor or contactor (IFC) is energized; indoor fan motor starts. Outdoor fan relay OFR is energized; outdoor fan motor runs. Compressor contactor C1 is energized; refrigeration circuit operates in Heating mode.

    this is from a 2009 service manual. Uncertain of actual serial # of unit in discussion. The way this sequence was described to me is; that control board is looking for what signal is NOT there when determining heat call, mainly the "Y" signal. Can't located the really old IOM that contained the T-stat set up.

  4. #30
    Join Date
    Jan 2010
    Posts
    19,281
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    Quote Originally Posted by Cool breeze 38 View Post
    that right. why would you need to configure the thermostat for electric heat?
    And why would the unit run in cooling if only w1 is energized. I'm referencing your previous comment


    VTP99 that pic doesn't show what the HR is doing on a call for w1. that's just the defrost cycle.
    .
    Attached Images Attached Images  

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