Error code reference

Lennox Furnace Error Code E 227

Low pressure switch open during trial for ignition or run mode.

First step from the service manual

Check pressure (inches w.c.) of low pressure switch closing on heat call. Measure operating pressure. Inspect vent and combustion air inducer for correct operation and restriction. Resumes normal operation after fault is cleared.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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Step-by-step tests with expected resistance, voltage, and continuity values
Wiring diagram references and connector pinouts from the OEM service manual
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E 227 on my Lennox Furnace

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Low pressure switch open during trial for

From Service Manual 269854, p.26:

1.Check pressure (inches w.c.) of low pressure switch closing on heat call. Measure operating pressure. Inspect vent and combustion air inducer for correct operation and restriction. Resumes normal operation after fault is cleared.

2.Inspect the exhaust duct from the unit to the wall cap. A crushed or lint-blocked duct is the most common cause of airflow-related faults.

3.Measure static pressure at the blower housing with the lint screen removed. Expected: ≥ 1.0 in. w.c. in a still-air test.

Part W10861225

Blower wheel and housing

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First step from the service manual

Get the full diagnostic procedure for E 227.

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