Quick Answer:
If the disposal only makes a steady hum and the grinding plate doesn’t turn, treat it as a jam. Immediately switch the unit off (or trip the breaker) and wait a minute. Prolonged humming without movement can overheat the motor; do not leave it running while you troubleshoot.
Why This Happens
A steady hum usually means the motor is getting power but the impeller or flywheel is blocked. Common causes are small hard objects, fibrous food caught between blades, or the flywheel seized after something like ice or broken parts jammed the chamber. The motor draws current and makes the humming sound, but it can’t build torque to turn when the rotor is stuck.
Occasionally electrical issues can sound similar, but the first assumption when you hear humming with no movement should be a mechanical jam. If you recently used ice or noticed a recent leak, check related troubleshooting guides like Disposal jam after ice cubes and Disposal won’t spin after leak for specific tips.
Step-by-Step What to Do
1. Cut the power
- Turn the disposal switch off. Then switch off the circuit breaker for that outlet to be sure the unit has no power.
- If the unit is plugged into an outlet under the sink, unplug it after turning the breaker off to be safe.
2. Confirm it’s a jam (listen first)
- With the power off, briefly restore power only long enough to flip the switch if you need to confirm the noise source—only if you are confident you can keep hands away. Better: listen before restoring power. If it hums without any movement for several seconds, treat it as a jam and cut power again.
- Do not let the unit run while you test; short hums that stop quickly can be normal during startup, but a sustained hum without motion is a sign of blockage or seized bearings.
3. Try the manual free-turn method
- Keep the power off at the breaker. Use a flashlight and look down the drain (do not put your hand inside) for visible foreign objects.
- Most disposals have a hex socket on the bottom. Insert the correct-sized hex wrench (usually 1/4″ or 3/8″) into that socket and turn it back and forth to free the flywheel. Use steady, firm pressure—do not use impact tools.
4. Remove trapped debris
- With power still off, use pliers or tongs to remove any visible objects through the sink opening. A wooden spoon handle can be used to gently nudge the flywheel if there’s no hex socket, but never put your hand inside.
5. Reset and test
- After you can turn the wheel freely by hand, restore power at the breaker and press the disposal’s reset button (if it has one).
- Turn on cold water and briefly run the disposal to test. If you hear the hum again without movement, stop immediately and cut power—do not keep running it.
What Not to Do
- Do not keep running water and hoping the hum “goes away”—treat it as a jam. Running the motor while it’s jammed can overheat and damage it.
- Do not put your hand down the drain. Use tools like pliers, tongs, or the correct hex wrench from the bottom of the unit.
- Do not use power tools to try to force the flywheel loose; this can break parts or create a dangerous situation.
- Do not remove electrical components or the motor housing while the unit is still powered.
When to Call a Professional
- If the flywheel won’t turn with the hex wrench or if the grinding chamber has broken parts, call a plumber or appliance technician.
- If the unit smells hot, trips the breaker repeatedly, or you see smoke, cut power and call a professional immediately.
- If you are uncomfortable working under the sink or cannot safely access the disposal, schedule a service visit rather than trying risky repairs yourself.
Safety Notes
- Always cut power at the breaker before working on the disposal. Flipping the wall switch is not always enough.
- Use tools—never your bare hands—inside the disposal opening.
- Wear eye protection and keep children and pets away while you work.
- If the motor has run while jammed, it may be overheated; allow it to cool before attempting manual turning and consider professional inspection if damage is suspected.
Common Homeowner Questions
- Why does it hum but not spin? A steady hum means the motor is powered but cannot rotate because something is blocking the flywheel or the unit has seized.
- Can I fix it myself? Often you can free a simple jam by cutting power, using the hex wrench, and removing debris—if you follow safety steps.
- Will running cold water help? No. Do not run water and keep operating the disposal while it hums; that risks overheating and damage.