Error code reference

Lennox Furnace Error Code LED1-OFF/LED2-SLOW_FLASH

Pressure switch open or has opened 5 times during a single call for heat; OR blocked inlet/exhaust vent; OR condensate line blocked; OR pressure switch closed prior to activation of combustion air blower.

SourceLennox G27M Series Furnace - Service Manualp. 5

Lennox codes Lennox furnace codes

Diagnostic procedure

The full LED1-OFF/LED2-SLOW_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.

MyPros+ · DiagnosticsStep 1 preview

First diagnostic step

Check pressure switch is open without combustion air blower operating; check for restricted inlet/exhaust vent; check condensate line.

SourceLennox G26 Series Furnace - Service Manualp. 12

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Where this code is documented

2 manuals in the MyPros+ library document this code for Lennox furnace.

Models covered by the manuals that document this code

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The full LED1-OFF/LED2-SLOW_FLASH procedure

Where this code is documented

Models covered by the manuals that document this code

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