Pump hums but does not start, then trips the overload or breaker

Safety first: Isolate power before touching the pump. Do not repeatedly reset a tripping breaker.

• Check for mechanical jam: Remove the pump lid and check for debris. If accessible, try to rotate the motor shaft by hand from the rear fan end. It should turn freely.
• Inspect capacitor (single‑phase): Locate the start/run capacitor in the motor terminal box. Look for bulging or leakage. Replace with an identical Lowara‑specified value if defective.
• Verify voltage: Measure supply voltage under start conditions. Significant drop indicates wiring or supply issues.
• Re‑test: After clearing jams and replacing any faulty capacitor, re‑prime and start the pump.
• When to call a pro: If the shaft will not turn or the pump still only hums, motor replacement is likely required.