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Furnace not working

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simp50
simp50 Member Posts: 2
in Gas Heating
Combustion air inducer runs continuously when power is on and thermostat off on a Lennox 80 uhh furnace

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  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,525
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    Disconnect the thermostat wires at the furnace and see if the inducer shuts down. If it does t stat or tstat wiring is defective.

    If it does shut down the control board or relay taht starts the inducer is probably defective
  • ratio
    ratio Member Posts: 3,626
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    Open limit?
    SuperTech
  • SuperTech
    SuperTech Member Posts: 2,164
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    ratio said:
    Open limit?
    That would be my first thought.  Open rollout or limit switch.  The control board on the furnace should indicate a fault code by flashing the LED, that should point you in the direction of the cause of your problem. 
  • HVACNUT
    HVACNUT Member Posts: 5,835
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    Inducer fan relay is stuck or shorted closed. Need a new circuit board. 
  • mikeapolis
    mikeapolis Member Posts: 46
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    Does switching the T-stat to "fan on" turn the blower on?
  • simp50
    simp50 Member Posts: 2
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    Thanks guys looks like I’m gonna have to get a control board 
  • Ironman
    Ironman Member Posts: 7,376
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    It's probably not the board, but an open limit or flame rollout switch.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Seabee5701
    Seabee5701 Member Posts: 19
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    Bad ignitor.....

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