Error code reference
Lennox Air Conditioner Error Code E437
Heat sink temperature sensor fault has occurred
Heat sink temperature sensor fault has occurred - temperature less than 4°F or greater than 264°F after 10 minutes of operation (inverter code 65).
First step from the service manual
Disconnect power to outdoor unit and restart. If problem persists, replace inverter.
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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