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How to turn off Continuous Fan on Lennox BCC2-1

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tspete
tspete Member Posts: 4
in Gas Heating
I've recently replaced my Lennox board (BCC2-1). And it has Continuous Fan on, so it's been blowing air (cold) when the heat is not on. I want to bypass the continuous fan option but I'm unsure how to do that. This is the setup of the board:

http://www.hawestv.com/ebaypictures/furnace/lennox_inst_no_btns.htm

Any ideas? I feel like the solution is easy and right in front of me, but I don't know how to approach it. Thanks

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  • ratio
    ratio Member Posts: 3,626
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    The paperworks you linked to don't show a continuous fan setting. Did you check that the fan switch is in 'auto' on the thermostat? After that, there is a fan off delay that will keep the fan on for at most ≈270 seconds, you're sure you aren't just seeing that?

    I'm not sure of the sequence of operations of that board, but certain faults (limit switches mostly) can result in the fan being energized; I wouldn't expect heating cycles if that were the case though.

    Then, if course, it could be a defective board or a wiring fault. I'd pull the G wire off & see if that makes it stop, then all the stat wires.

    DZorotspete
  • rick in Alaska
    rick in Alaska Member Posts: 1,457
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    Some furnaces have the ability to turn the fan on from inside the furnace itself. Look at he control board and see if there is a switch on it that just says fan, and if it does, just turn it off and the furnace will run normally. But, only if you followed Ratio's advice and it is still on.
    Rick
    tspete
  • tspete
    tspete Member Posts: 4
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    There’s a switch from the motor to the Lennox board. It’s a red wire to the switch then connected to the continous fan (CT) terminal. I’ve switched it both ways and it doesn’t seem to change anything. The fan runs when I turn power on. I even tried disconnecting the red wire from the CT terminal.

    Everything is else is working perfectly. It’s just the fan.

    Also, I have a Nest smart thermostat. It doesn’t have a fan auto control. My house is old and only has the W and R wires connected to the Nest thermostat.
  • ratio
    ratio Member Posts: 3,626
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    Sounds like the board is bad. If the board has a CT or CF or CONT terminal for continuous fan, all the others should be de energized when idle, delay timers not withstanding. One of them is stuck on.

    post pics of the board showing the wires & terminals, & maybe one of the schematic.

  • DZoro
    DZoro Member Posts: 1,048
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    Unhook the red wire to the CT switch. See what happens.
  • tspete
    tspete Member Posts: 4
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    DZoro said:

    Unhook the red wire to the CT switch. See what happens.

    Tried that, fan still runs continuously :(

  • tspete
    tspete Member Posts: 4
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    ratio said:

    Sounds like the board is bad. If the board has a CT or CF or CONT terminal for continuous fan, all the others should be de energized when idle, delay timers not withstanding. One of them is stuck on.

    post pics of the board showing the wires & terminals, & maybe one of the schematic.

    Here is a diagram, I’ll take a pic as soon as. Can
    http://www.hawestv.com/ebaypictures/furnace/lennox_inst_no_btns.htm

  • DZoro
    DZoro Member Posts: 1,048
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    Take off the stat wires R & W. Does the fan still run?
  • workflow
    workflow Member Posts: 1
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    Is this problem solved? I have exactly the same issue here after I replaced the ignition control module. It shouldn't impact the BCC2 board but now the fan runs nonstop at low speed, starting 45 seconds after power is restored to furnace. I can run the fan (at high speed) from my Nest, but I can't seem to turn off this continuous running slow fan mode. The CF terminal on the BCC2 board is not connected.

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