Furnace attempts to start, fan runs but burner does not ignite, display shows 03

Safety: Disconnect power before removing the front cover or accessing the fan or flue connections.

Steps:

• 1. Check flue terminal: Go outside and inspect the concentric flue terminal. Remove any visible obstructions such as leaves, plastic bags, or ice. Ensure the terminal clearances meet local codes.
• 2. Listen to the fan: When a heat demand is present, the fan should start before ignition. If you hear no fan noise, the fan may be seized or not powered.
• 3. Inspect fan area: With power off, remove the combustion chamber cover. Check the fan wheel for debris or signs of water ingress. Try to rotate the fan impeller gently; it should spin freely without grinding.
• 4. Check fan connections: Ensure the fan plug is firmly seated on the motor and on the main PCB. Look for burnt connectors.
• 5. Technician tests: A technician can measure supply voltage to the fan during start-up and check the fan speed feedback signal. If voltage is present but the fan does not run, replace the flue gas fan assembly. If the fan runs but the board does not detect speed, check the Hall sensor or replace the fan or PCB as specified by Immergas.