Display shows A03, furnace stops and may attempt restart, overheat indicator lit on control board

Safety: Turn off power at the main switch. Do not bypass safety thermostats.

• Check airflow: Inspect and replace or clean the return air filter. Ensure all supply and return grilles are open and not blocked by furniture or rugs.
• Inspect blower fan: Remove the blower compartment cover. Check that the Beretta circulation fan wheel is free of dust buildup and can spin freely by hand. Clean the blades with a brush and vacuum. Do not bend the blades.
• Reset safety thermostat: Many Beretta furnaces have a manual reset safety thermostat on the heat exchanger or flue hood. Look for a small round device with a red button. Once the unit has cooled, press the button to reset. If it trips repeatedly, do not continue resetting—find and correct the cause.
• Check for blocked heat exchanger or flue: Visually inspect the primary heat exchanger area for heavy soot or debris. Check that the flue connection is not crushed or blocked. Any sign of soot or corrosion requires professional service.

Persistent A03 faults indicate a serious overheating or airflow problem and should be evaluated by a qualified technician.