Error code reference

Lennox Air Conditioner Error Code E422

Compressor top cap switch exceeding thermal limit.

Compressor top cap switch exceeding thermal limit.

First step from the service manual

Check that wires from the top cap switch are properly connected to the TP terminals on the outdoor control board.

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

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E422 on my Lennox Air Conditioner

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Compressor top cap switch exceeding thermal

From Service Manual 873197, p.49:

1.Check that wires from the top cap switch are properly connected to the TP terminals on the outdoor control board.

2.Measure door lock assembly resistance across the PTC terminals. Expected: ~200 ohms cold, rising sharply once energized.

3.Inspect strike and latch alignment. A warped door or misaligned strike prevents the switch stack from closing in the correct sequence.

Part W10810403

Door lock assembly

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