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hot air furnace problem

Paul@P.C. Htg.
Paul@P.C. Htg. Member Posts: 1
in THE MAIN WALL
80% hot air furnace in atic. P.C. got wet. Changed p.c. board and flame sensor. Furnace has hot surface ignitor. Furnace goes through starting sequence and lights. Have full flame for approx. 3 or 4 seconds then shuts down. Retries to start 3 more times then shuts down. Panel light blinks 4 times indicating ignition failure check ground. We have checked ground and even tried another pc board. NEED HELP.

Comments

  • steve_93
    steve_93 Member Posts: 37


    Make sure flame sensor is in contact with flame.
  • Dan Foley
    Dan Foley Member Posts: 1,266
    Flame Failure

    I would check these:

    1. Polarity

    2. Clean the flame sensor

    3. Make sure the ceramic on the flame sensor is not cracked

    4. Change the flame sensor wire. This circuit measure micro-amps in most systems. I have found flame sensor wires that appeared fine visually but were in fact causing a problem.

    Good Luck! -DF

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  • Empire_2
    Empire_2 Member Posts: 2,340
    Dry dry dry

    Make sure the whole thing is dry. I mean all moisture gone. Check with micro amp meter, sounds like you are not getting any signal at all. You may have a very weak short that is canciling out you flame signal, but not tripping lo volt fuse...
  • tom_49
    tom_49 Member Posts: 269


    What make/model furnace? If its the ever popular Goodman, try running a peice of wire from FS right to board ( bypassing molex connector ).
  • Unknown
    Unknown
    You still have moisture

    somewhere. The boards see moisture as an AC signal on the sensing circuit and will not fire. I suggest taking everything apart and drying it out with a fan. How much moisture did you get? Reason I ask is that GAMA recommends replacing the entire unit if it has been under water, flooded, or soaked in any way. Homeowners insurance will usully cover it.

    I have seen jobs that got wet and we chased them for several weeks until frustration set in - replaced unit problem goes away. It is not my usual way to do things as I like to fix things but .... sometimes you have no choice.
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