Error code reference
Lennox Air Conditioner Error Code E438
The inverter has detected a PFC over current condition caused by a high load condition, high pressure, or…
The inverter has detected a PFC over current condition caused by a high load condition, high pressure, or outdoor fan failure (inverter code 73).
First step from the service manual
Check for high pressure trips or other alert codes in room thermostat and outdoor control.
The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.
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- 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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