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…
The outdoor control has lost communication with either the thermostat or indoor unit due to numerous message errors, typically related to electrical noise.
First step from the service manual
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.
The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.
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Get the full diagnostic procedure for E105.
- Step-by-step tests with expected resistance, voltage, and continuity values
- Wiring diagram references and connector pinouts from the OEM service manual
- Verified part numbers when replacement is required
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