lennox furnace

Old 12-16-10, 09:00 PM
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lennox furnace

I have a lennox furnace model #80mgf3-75a-1. Please forgive my inexperience with terminoogy. The fan/motor on the upper part of the furnace runs almost all the time. The furnace filter was horribly filthy, which I replaced. I have lightly sanded each of the three sensors in front of the burners. The circuit board has a flashing red light but I do not see a pattern to the flashing just constant flashing. Any help would be appreciated. thank you
Old 12-16-10, 09:51 PM
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The manual for your furnace is here:


There should be two diagnostic lights.

Perhaps you can identify the pattern from among those given beginning on page 40 of the manual.
Old 12-19-10, 09:08 AM
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you probalbly have a tripped high limit switch that may need to be reset

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