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    Help! Furnace only blowing cold air (4 Posts)

  • Noheathelp Noheathelp @ 9:16 AM
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    Help! Furnace only blowing cold air

    Hope someone can help me trouble shoot. I have no HVAC experience. We live in the Midwest and have -20 degree weather today and our furnace is blowing out cold air. When I turn the switch on/off attached to the furnace it kicks heat for a minute. Then keeps blowing cold air.

    Thoughts? I appreciate the help while we wait for the overworked HVAC company to call us.
  • M Lane M Lane @ 10:01 AM
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    Do this

    ***The following will only work if you have a semi-modern or newer furnace***
    Take the front panel off, but not the one where the blower is (there is a door switch). Cycle power off and back on again to reset the unit. Observe where the burners are. Do the flames kick on, then drop off? If so, you have a dirty flame sensor. To continue, you need a modicum of mechanical aptitude.
    The burners will have 2 devices wired in inside the combustion area. One would be the igniter, the other that looks like a thin metal rod is the flame sensor. If you can brush off the white stuff on it with clean steel wool or a clean scrubber pad, this might do the trick. DON'T DO ANYTHING WITHOUT TURNING OFF THE POWER FIRST! This is only one idea from many possible causes you might have, but it is common too.
    KEEP IN MIND THAT YOU ARE DEALING WITH A MACHINE THAT CAN KILL YOU IF YOU DO THE WRONG THINGS!
    This post was edited by an admin on January 6, 2014 10:02 AM.
  • RJ RJ @ 10:19 AM
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    filter

    Check for a dirty furnace filter or obstructed return air to furnace,  Some older furnaces will cycle the fan on when the furnace goes off on high limit  (return air temp gets to hot )
    RJ
  • unclejohn unclejohn @ 9:25 AM
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    Change

    The air filter.
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