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  1. #1

    Lennox 80MG Furnace, Multiple Issues

    Hello all,
    I have a Lennox furnace which is about 14 years old, it has worked flawlessly until a few days ago. There have been multiple issues which have had myself and a friend of mine perplexed:
    At that point I heard a clunking sound coming from my furnace, which I was able to find was the gas valve. If the gas valve were unplugged, a clicking could be heard from the board.
    After resetting the board, the issue starts again.
    Another issue which has come up is the fan to blow away obstructions (attached to pressure switch) will go on, blow, shut with diagnostic showing an obstruction, and then start again.
    I have also had the issue where the gas will light for a few seconds, then go out. It cycled through until the fifth time when it finally stayed on.
    AS of now, it is working fine, although it could start having problems again soon. I believe the problem to be the control board but want to get another opinion before buying one.
    If I could clarify anything, please let me know.
    Info:
    Lennox 80MGF4/5-120A-7
    Board EGC-2
    Thanks,
    JDH313

  2. #2
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,415
    You could have a partial obstruction in the flue pipe.

  3. #3
    We tried that, we removed the exhaust pipe and still had those issues.
    Thank you though.

  4. #4
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,415
    Flame sensor and/or pressure switch could be the issue. It's hard to see w/o being on the job. Parts are expensive just to guess at. A tech could find out what is the exact problem and you won't be buying a bunch of parts that may not fix the problem.

  5. #5
    Join Date
    Feb 2010
    Location
    Calgary, Alberta
    Posts
    1,130
    Inducer motor is probably weak. Common problem on that furnace.
    Control boards on that furnace have been revised many times by Lennox and are still an issue.

    You have a builder grade furnace that needs a bunch of costly repairs.
    Call a pro and get an estimate for replacement.

  6. #6
    Join Date
    Aug 2012
    Location
    North Dakota
    Posts
    518
    MULTIPLE ISSUES REALY MEAN MANY $$$ SPENT START FRESH AND DO YOUR HOMEWORK FIND THE RITE CONTRACTOR ASK ARROUND , LOOK AT THEIR WORK FIND OUT WHAT HAPPENS WHEN THEIR CUSTOMERS HAVE TROUBLES WITH THEIR EQUIPMENT, GET REFRENCES AND CHECK THEM!!! ANY EUIPMENT IS ONLY AS GOOD AS ITS INSTALLER

  7. #7
    Is the motor painted black ?
    If so the problem is with the paint they used on a small number of furnaces, the paint would peel off and enter the vacuum lines to the pressure switch . If this is the problem then you should replace inducer motor,pressure switch, and vacuum lines.

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