Lennox Ducted Heating

Lennox Ducted Heating Error Code Fast Flash

Ducted Heating

Fast Flash means different things on different Ducted Heating models. Enter your model number to see only your reading, or find your model below.

What It Means

  • G24M: Loss of Flame Sensed Before End of 45 second Blower On Delay (3 or Fewer Trials for Ignition)
  • G24M: Normal Operation with Call For Heat
  • LF24: Normal Operation - Call for heat
  • TUA*S(N,L)(A,S)F: Normal Operation - Call for heat Current signal at FLAME terminal 0.6 to 1.0 microamps

Causes & actions from Lennox

Loss of Flame Sensed Before End of 45 second Blower On Delay (3 or Fewer Trials for Ignition)

Models: G24M

How it shows
  • a3 diagnostic led: Fast Flash

Combustion Air Blower: On Gas Valve: Off Then On With Spark After Pre- Purge Supply Air Blower: On

Other manual wording

G24M

Combustion Air Blower: On Gas Valve: On (Spark Starts Within 0.8 seconds) Supply Air Blower: On

Applicable models & manual sources
  • G24M

    Loss of Flame Sensed After 45 second Blower On Delay (3 or Fewer Trials for Ignition)

    G24M manual, page 12

  • G24M

    Loss of Flame Sensed Before End of 45 sec- ond Blower On Delay (3 or Fewer Trials for Ignition)

    G24M manual, page 12

Normal Operation with Call For Heat

Models: G24M

How it shows
  • a3 diagnostic led: Fast Flash

This manual entry does not list further causes or actions.

Applicable models & manual sources

Normal Operation - Call for heat

Models: LF24

How it shows
  • integrated control single led: Fast Flash

This manual entry does not list further causes or actions.

Applicable models & manual sources

Normal Operation - Call for heat Current signal at FLAME terminal 0.6 to 1.0 microamps

Models: TUA*S(N,L)(A,S)F

Unit heater (indoor)

How it shows
  • integrated control single led: Fast Flash

This manual entry does not list further causes or actions.

Applicable models & manual sources
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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