Pahlén variable-speed pool pump shows E03 and stops shortly after starting

Safety first: Turn off power at the breaker before touching the motor housing. Allow the motor to cool fully before inspection.

• Check ventilation: Ensure the Pahlén pump motor has at least several centimeters of clearance on all sides. Remove leaves, dust, or cobwebs from cooling fins and ventilation slots.
• Inspect the fan: At the rear of the motor, verify that the cooling fan is intact and spins freely. If the fan is broken or missing, the motor will overheat and must be repaired or replaced.
• Reduce load: Confirm that valves on the discharge side are not excessively throttled. Extremely high backpressure can overload the pump. Open return valves fully and ensure the filter is clean.
• Check ambient conditions: If the pump is in a closed plant room, improve ventilation or add an exhaust fan to reduce temperature around the Pahlén equipment.
• Reset: After cooling and correcting airflow issues, restore power and clear E03 on the control panel. Monitor the motor temperature during operation.

If E03 recurs quickly, the internal thermal sensor or motor windings may be damaged and require professional diagnosis.