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rwcrazy Member Posts: 1
Michigan sucks... anyways, my furance is about 22 years old, (I know should replace), but anyways it just started this issue. It will work fine for days on end, then it will just not run right. When the temp goes low the exhaust blower will kick on and then usually you can hear the igniter starting and it will run like normal, but what has been happening is the exhaust blower will run and run and run, the ignitor will never even try and kickt on to start it.. If I turn the switch on the thermostat on and off a couple times it will finally start working again... I replaced the thermostat wire and the thermostat.. any help would be great... Thanks


  • Ironman
    Ironman Member Posts: 6,900
    Not enough info...

    For an accurate diagnosis, but a safety in the control circuit may be causing power to be interrupted to the igniter.

    The two most likely would be:

    1. A vent pressure switch which would point to blockage in the vent, collector or condensate drain if it's a 90% + furnace.

    2. A limit switch which could mean something as simple as a dirty filter or as serious as a bad heat exchanger.

    The igniter itself may be cracked if it's hot surface type.

    It would not be in the thermostat or its wiring if the draft inducer was running.

    I'd really recommend you get a pro and not attempt any DIY repairs.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • icesailor
    icesailor Member Posts: 7,265
    edited February 2014
    X 4:


    Its hard enough for professionals to troubleshoot a gas furnace and they know what they are doing, mostly.

    For a rookie DIY to do it can put life and limb in jeopardy.

    Turning off the power to the furnace resets the control that decided that the system wasn't functioning and stops it. Keeping the fan running is a way to protect the heat exchanger from over heating and cracking. Turning the thermostat up and down has no effect on the operation of the safety switches.

    If you have to reset the controls/furnace more than once a week, you need service, and professional service person to look at it. More than once a day, you definitely need professional help.

    Its like a cancer. It won't get better if you ignore it. It only gets worse.