Lennox Ducted Heating

Lennox Error Code LED #1: SLOW FLASH, LED #2: ON

Ducted Heating:

What It Means

  • Primary or Secondary limit open. Units with board 63K8901 or 24L85: Limit must close within 5 trials for ignition or board goes into one hour limit Watchguard. Units with board 56L83 or 97L48: Limit must close within 3 minutes or board goes into one hour limit Watchguard.

Causes & actions from Lennox

How it shows
  • SureLight board LEDs (DS1/DS2): LED #1: SLOW FLASH, LED #2: ON (led1: flashing (slow), led2: on)

This manual entry does not list further causes or actions.

Applicable models & manual sources
  • G24M

    Primary or Secondary limit open. Units with board 63K8901 or 24L85: Limit must close within 5 trials for ignition or board goes into one hour limit Watchguard. Units with board 56L83 or 97L48: Limit must close within 3 minutes or board goes into one hour limit Watchguard.

    G24M manual, page 9

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

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