Error code reference

Lennox Air Conditioner Error Code E429

DC link power in inverter does not rise above threshold (180 VDC for 2/3-ton, 250 VDC for 4/5-ton) within 30…

DC link power in inverter does not rise above threshold (180 VDC for 2/3-ton, 250 VDC for 4/5-ton) within 30 seconds (inverter code 23).

First step from the service manual

Check for proper main power to outdoor unit and for any loose electrical connections.

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

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E429 on my Lennox Air Conditioner

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DC link power in inverter does not rise above

From Service Manual 873190, p.42:

1.Check for proper main power to outdoor unit and for any loose electrical connections.

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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