Error code reference

Carrier Furnace Error Code 31

Pressure switch did not close or reopened; if open longer than 5 minutes, inducer shuts off for 15 minutes…

Pressure switch did not close or reopened; if open longer than 5 minutes, inducer shuts off for 15 minutes before retry.

First step from the service manual

Check for proper vent sizing, low inducer voltage (115VAC), defective inducer motor, defective pressure switch, inadequate combustion air supply, disconnected or obstructed pressure tubing, low inlet gas pressure (if LGPS used), restricted vent, or excessive wind.

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
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