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How to turn off Continuous Fan on Lennox BCC2-1

tspetetspete Posts: 4Member
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

Comments

  • ratioratio Posts: 1,665Member
    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.

  • rick in Alaskarick in Alaska Posts: 762Member
    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
  • tspetetspete Posts: 4Member
    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.
  • ratioratio Posts: 1,665Member
    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.

  • DZoroDZoro Posts: 477Member
    Unhook the red wire to the CT switch. See what happens.
  • tspetetspete Posts: 4Member
    DZoro said:

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

    Tried that, fan still runs continuously :(

  • tspetetspete Posts: 4Member
    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

  • DZoroDZoro Posts: 477Member
    Take off the stat wires R & W. Does the fan still run?
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