Error code reference

Lennox Heat Pump Error Code Simultaneous SLOW Flash (Green/Red)

Normal operation

Normal operation — unit operating normally or in standby mode.

First step from the service manual

None required.

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 Simultaneous SLOW Flash (Green/Red).

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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Simultaneous SLOW Flash (Green/Red) on my Lennox Heat Pump

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Normal operation — unit operating normally or

From Service Manual 659140, p.32:

1.None required.

2.Measure control board supply voltage at the test points. Expected: 12 VDC and 5 VDC; a drop below 4.75 VDC on the logic rail points to a failed onboard regulator.

3.Inspect all connectors on the main control for corrosion, thermal stress, or backed-out pins. Reseat each connector with the power disconnected.

Part WPW10804018

Electronic control board

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First step from the service manual

Get the full diagnostic procedure for Simultaneous SLOW Flash (Green/Red).

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