Heater shows E12 and will not start; internal fan may run continuously

Safety: Turn off power and allow the heater to cool. Do not cover or enclose the heater while operating.

• Check clearances: Ensure the SunHeater has the minimum side, rear, and top clearances specified in the manual. Remove any stored items, pool chemicals, or covers blocking airflow.
• Inspect internal fan (if equipped): Some models use an internal cabinet fan. Confirm the Cabinet Cooling Fan spins freely and runs when the heater is operating. Replace if seized or noisy.
• Clean air passages: Use a vacuum and soft brush to remove dust and cobwebs from louvers, grilles, and around the control compartment.
• Check internal temperature sensor: Locate the Cabinet Temperature Sensor on the control panel or near the top of the cabinet. Inspect wiring and test resistance per the service chart. Replace if out of range.
• Test in cooler conditions: If the heater is installed in a small shed or equipment room, improve ventilation or open doors/windows during operation. Persistent E12 in hot weather may require relocating the heater or adding ventilation.