Lennox thermostat shows E430 indoor humidity sensor error; dehumidification features may not work correctly during cooling.

Safety: Turn off power to the thermostat (if hard-wired) and indoor unit before removing covers.

• 1. Clean thermostat sensor vents: If the humidity sensor is integrated into the Lennox thermostat, gently vacuum or blow dust from the side vents.
• 2. Inspect remote humidity sensor: If a separate return-duct sensor is used, check its mounting and wiring. Ensure it is not directly in the path of supply air or near a humidifier outlet.
• 3. Reseat connections: At the indoor control board, unplug and reconnect the humidity sensor terminals or plug.
• 4. Replace faulty sensor: If readings are obviously wrong (e.g., 10% or 99% constantly), replace the sensor with the correct Lennox part.

Note: While this may not stop cooling, it affects comfort and dehumidification control.