Lennox Ducted Heating

Lennox Error Code LED 1 Alt. Slow Flash / LED 2 Alt Slow Flash

Ducted Heating:

What It Means

  • Ignition Watchguard. Four-second ignition trial: ignitor energized1second after valve opens, no flame sensing during this1second;97L48 board energizes ignitor during trial or until flame sensed. Flame rectification proven within4seconds after valve opens, greater than0.15microamps. Five consecutive unsuccessful tries in one demand OR ignition sequence reset four times from flame-loss branch gives Watchguard: gas valve OFF, combustion inducer OFF, indoor blower OFF with delay; both lamps alternating slow flash;60minute reset.

Causes & actions from Lennox

How it shows
  • SureLight board LEDs (DS1/DS2): LED 1 Alt. Slow Flash / LED 2 Alt Slow Flash (led1: flashing (slow), led2: flashing (slow))

Ignition Watchguard mode. Control failed to sense flame for five consecutive tries during a single heat demand. Gas valve off, combustion air inducer off, indoor blower off with delay.

Applicable models & manual sources
  • G24M

    Ignition Watchguard. Four-second ignition trial: ignitor energized1second after valve opens, no flame sensing during this1second;97L48 board energizes ignitor during trial or until flame sensed. Flame rectification proven within4seconds after valve opens, greater than0.15microamps. Five consecutive unsuccessful tries in one demand OR ignition sequence reset four times from flame-loss branch gives Watchguard: gas valve OFF, combustion inducer OFF, indoor blower OFF with delay; both lamps alternating slow flash;60minute reset.

    G24M manual, page 28

Disclaimer: This information is for general reference. Code wording and instructions vary by model. Always follow the service manual for your exact unit.

What should you check next?

Continue in ACLogics with guided diagnosis for your equipment and symptoms.

Download on the App Store Get it on Google Play
Scan to install on your phone Free · iPhone & Android
See how guided diagnosis works →