Harris variable-speed pump shows E05 and stops running, often after running for some time

Safety first: Turn off power at the breaker and allow the pump to cool before inspection.

• Check ventilation clearance: Ensure there is adequate space (per Harris manual, typically at least several inches) around the motor and control housing for airflow. Remove leaves, mulch, or debris blocking vents.
• Clean cooling passages: Use a soft brush or compressed air to clean dust and debris from the motor cooling fins and any external fan openings. Do not spray water directly into the control module.
• Inspect motor bearings: With power OFF, spin the motor shaft by hand. If it feels rough, gritty, or noisy, the bearings may be failing and generating excess heat.
• Check run speed and duty cycle: If the pump is programmed to run at maximum RPM continuously in hot weather, reduce the speed or add rest periods to lower heat load.

If E05 recurs even with good ventilation and normal load, the internal drive or motor may be overheating due to internal faults and should be evaluated for replacement.