Pool Pump Humming but Not Running: Causes
A humming pump that won't spin is getting power but can't turn. Turn it off. Leaving a stalled motor energized can overheat it and turn a small repair into a big one.
Common causes
1. Failed start capacitor
Many single-speed motors use a capacitor to start. When it fails, the motor hums and may spin if nudged. Capacitors hold a charge, so a homeowner shouldn't test or replace one. That's a job for a technician.
2. Jammed impeller
Leaves, seed pods, small rocks or pieces of a toy can lock the impeller. With the breaker off, you can open the pump basket and clear any debris you can see.
3. Seized bearings
If the motor screeched or ground for weeks before it stopped, the bearings may be gone. Usually that means a motor replacement.
4. Low voltage or wiring problems
Loose connections, a failing breaker or a wiring problem can keep the motor from starting. That's for an electrician or pool tech.
5. Variable-speed drive faults
Variable-speed pumps have electronic drives that show error codes. Write down the code and check the manual.
What's safe to check
- Turn the pump off at the breaker.
- Clear the skimmer and pump baskets.
- Look for obvious damage or burn marks, but don't open the motor.
- Note any error codes.
Call when
The pump still won't run, the breaker trips, or you smell burning. See pump repair & replacement.
Electrical work around water is dangerous. When in doubt, leave it off and call a professional.