What It Means
- After15second prepurge and20second ignitor warm-up, sequential voltage above75volts / proper ground / ignitor intact-connected tests: NO at any test produces alternating fast flash on both lamps.
Lennox Ducted Heating
Lennox Error Code Alternating Fast Flash
Ducted Heating:
Causes & actions from Lennox
How it shows
- SureLight board LEDs (DS1/DS2): Alternating Fast Flash (led1: flashing (fast), led2: flashing (fast))
Line voltage below 75 volts, improper ground, or ignitor is not intact and connected.
Applicable models & manual sources
- G24M
After15second prepurge and20second ignitor warm-up, sequential voltage above75volts / proper ground / ignitor intact-connected tests: NO at any test produces alternating fast flash on both lamps.
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.
