Error code reference

Lennox Air Conditioner Error Code E440

Heat sink temperature is approaching limit (inverter code 13); compressor speed automatically slows to reduce heat sink temperature.

SourceLennox Air Conditioner - Service Manual: Elite Series XC20p. 34

Lennox codes Lennox air conditioner codes

Diagnostic procedure

The full E440 procedure

Step 1 is visible so you can confirm you are on the right page. The remaining steps, the ones that tell you whether to actually replace a part, unlock with any pass.

MyPros+ · DiagnosticsStep 1 preview

First diagnostic step

Tighten screws that hold the heat sink to the inverter control board. Wait 5 minutes to allow capacitor to discharge before checking screws.

SourceLennox Air Conditioner - Service Manual: Elite Series XC20p. 34

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More steps, wiring diagram references, and verified part numbers

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Where this code is documented

2 manuals in the MyPros+ library document this code for Lennox air conditioner.

Models covered by the manuals that document this code

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The full E440 procedure

Where this code is documented

Models covered by the manuals that document this code

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