Lennox Error Codes

Error codes for Lennox appliances organized by type.

400Error Codes

4Appliance Types

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Reverse line voltage polarity

From Service Manual 723187, p.39:

1.Access service mode to confirm the active fault code and read stored error history.

2.Measure line voltage at the power cord terminal block. Expected: 120 VAC (L1 to neutral) or 208 to 240 VAC between L1 and L2 under load.

3.Inspect the cord strain relief and terminal block screws for signs of arcing or heat discoloration. Loose connections here mimic an intermittent power failure to the control board.

Part W10911048

Power cord assembly

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