Error code reference

Lennox Hvac Error Code 3 Flashes

Pressure switch open or closed, or auxiliary limit open (code will not appear until after indoor blower has…

Pressure switch open or closed, or auxiliary limit open (code will not appear until after indoor blower has been de-energized for approximately 120 seconds).

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Pressure switch open or closed, or auxiliary

From Service Manual 602911, p.43:

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

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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