Error code reference

Lennox Heat Pump Error Code DS2 SLOW Flash / DS1 OFF

High Pressure Fault

High Pressure Fault — one strike added to high pressure fault counter.

First step from the service manual

1. Remove blockages/restrictions from coils and fans; check indoor and outdoor fan motor current draws. 2. Check system charge using approach & subcooling temperatures. 3. Check system operating pressures and compare to charging charts. 4. Verify all pressure switches and sensors have secure connections.

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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DS2 SLOW Flash / DS1 OFF on my Lennox Heat Pump

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High Pressure Fault — one strike added to high

From Service Manual 922260, p.32:

1.1. Remove blockages/restrictions from coils and fans; check indoor and outdoor fan motor current draws. 2. Check system charge using approach & subcooling temperatures. 3. Check system operating pressures and compare to charging charts. 4. Verify all pressure switches and sensors have secure connections.

2.Measure door lock assembly resistance across the PTC terminals. Expected: ~200 ohms cold, rising sharply once energized.

3.Inspect strike and latch alignment. A warped door or misaligned strike prevents the switch stack from closing in the correct sequence.

Part W10810403

Door lock assembly

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First step from the service manual

Get the full diagnostic procedure for DS2 SLOW Flash / DS1 OFF.

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