Lennox Furnace Error Code LED1 Alternating Fast Flash / LED2 Alternating Fast Flash
Improper main ground (controls 10M93, 57L84 during ignitor warm up only; controls 78M47 & 100973-01 continuously), or broken ignitor (10M93, 57L84), or open ignitor circuit (78M47 & 100973-01), or line voltage below 75V (10M93, 57L84) or 90V (78M47 & 100973-01).
SourceLennox G40UH Series - Service Manual: Gas Furnacep. 18
The full LED1 Alternating Fast Flash / LED2 Alternating Fast Flash procedure
Step 1 is visible so you can confirm you are on the right page. The remaining steps, the ones that tell you whether to actually replace a part, unlock with any pass.
SourceLennox G40UH Series - Service Manual: Gas Furnacep. 18
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Where this code is documented
16 manuals in the MyPros+ library document this code for Lennox furnace.
Models covered by the manuals that document this code
- 90UGFA2-50
- 90UGFA3-50
- 90UGFA3-75
- 90UGFA3/4-100
- 90UGFA4/5-125
- F8AUH**-24-045
- F8AUH**-24-045X
- F8AUH**-24-060
- F8AUH**-24-075
- F8AUH**-36-060
- F8AUH**-36-060X
- F8AUH**-36-075
- F8AUH**-36-075X
- F8AUHX
- G23Q2(X)-50
- G23Q2/3(X)-75
- G23Q3(X)-100
- G23Q3(X)-50
- G23Q3/4(X)-100
- G23Q3/4(X)-125
- G23Q4/5(X)-100
- G23Q4/5(X)-75
- G23Q5/6(X)-125
- G23Q5/6(X)-150
More models are covered than are listed here.
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