Error code reference

Lennox Heat Pump Error Code DS2:SlowFlash / DS1:ON

Discharge line temperature fault

Discharge line temperature fault — discharge line temperature exceeded 285°F (140°C) during compressor operation; detects shorted sensor or high discharge temperatures.

First step from the service manual

Check for restricted airflow, improper charge, improper metering device, or incorrect sensor location. Compressor remains off until discharge temp drops below 225°F (107°C).

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 DS2:SlowFlash / DS1:ON.

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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DS2:SlowFlash / DS1:ON on my Lennox Heat Pump

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Discharge line temperature fault — discharge

From Service Manual 195570, p.22:

1.Check for restricted airflow, improper charge, improper metering device, or incorrect sensor location. Compressor remains off until discharge temp drops below 225°F (107°C).

2.Inspect the exhaust duct from the unit to the wall cap. A crushed or lint-blocked duct is the most common cause of airflow-related faults.

3.Measure static pressure at the blower housing with the lint screen removed. Expected: ≥ 1.0 in. w.c. in a still-air test.

Part W10861225

Blower wheel and housing

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First step from the service manual

Get the full diagnostic procedure for DS2:SlowFlash / DS1:ON.

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