Error code reference

Lennox Air Conditioner Error Code E105

The outdoor control has lost communication with either the thermostat or indoor unit due to numerous message errors, typically related to electrical noise.

SourceLennox XC25 Series - Full Service Manual: Installation & Operationp. 30

Lennox codes Lennox air conditioner codes

Diagnostic procedure

The full E105 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

Make sure high voltage power is separated from RSBus. Check for mis-wired and/or loose connections between the thermostat, indoor unit and outdoor unit.

SourceLennox Air Conditioner - Service Manual: Elite Series XC20p. 30

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More steps, wiring diagram references, and verified part numbers

Includes expected resistance and voltage values, connector pinouts, and supersession notes for replacement parts.

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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 E105 procedure

Where this code is documented

Models covered by the manuals that document this code

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