Error code reference
Lennox Heat Pump Error Code Alternating SLOW Flash
5-minute anti-short cycle delay (initial power up, safety trip, or end of room thermostat demand).
5-minute anti-short cycle delay (initial power up, safety trip, or end of room thermostat demand).
First step from the service manual
None required (Jumper TEST pins to override).
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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