Thermostat shows humidity but whole-home humidifier does not run when expected

Safety: Turn off power to furnace/air handler and humidifier transformer before working on wiring. Water may be present near electrical components.

• Step 1 – Verify ecobee humidifier settings: In Equipment, ensure the humidifier is enabled and the correct type (evaporative/steam) and control (on with heat, independent) are selected.
• Step 2 – Inspect wiring: Confirm the humidifier is wired to the ACC terminals (or designated humidifier terminals) per ecobee’s diagram, and that the humidifier’s own transformer/relay is powered.
• Step 3 – Test humidifier manually: Temporarily jumper the humidifier’s control terminals (e.g., HUM to C or across the solenoid) to see if it activates. If it does, the issue is with control wiring or ecobee output.
• Step 4 – Replace solenoid or relay if failed: If the humidifier does not run even when manually energized, the solenoid valve or relay may be defective and should be replaced.