Lennox furnace does not ignite

Old 04-09-18, 07:14 PM
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Lennox furnace does not ignite

Single stage gas furnace in a 1 story house.
Model number: ML180UHE
  • Ac works fine.
  • Furnace stopped working suddenly and will not work.
  • No error codes from board
  • For diagnosing, Stat W wire is connect to Rh to dive constant heat signal

Sequence of events.
  1. Blower motor turns on
  2. Pressure sensor senses low pressure
  3. Ignitor turns on for 20 seconds as specified timeline in the manual
  4. Gas valve should now turn on for 4 seconds.
    1. Does not turn on
    2. No voltage detected
    3. I heard a click from the board
    4. Ignitor immediately turns off after the 20 seconds (I would think this would stay on during the 4 seconds)
  5. This cycle repeats indefinitely

Any help would be appreciated.

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