Why does my garbage disposal hum but not spin?

The hum is actually good news. It means the motor is getting power and trying to turn — the unit is jammed, not burned out. Left humming, though, it will overheat, so switch it off before working through this.

The sequence

• Turn off the disposal at the switch, then cut power at the breaker. A wall switch is not sufficient protection when your hands are near the chamber.
• Look into the chamber with a flashlight. Usually something identifiable is wedged against the impellers — a bottle cap, a bone fragment, a fruit pit, a piece of cutlery.
• Remove it with tongs or pliers. Never with fingers, even with the breaker off. This is worth being rigid about.
• Find the hex wrench that came with the unit (often clipped to the underside) and fit it into the socket in the very centre of the disposal’s base. Work it back and forth. That turns the grinding plate directly and breaks most jams.
• Press the small red reset button, also on the base. A motor that has stalled trips its thermal overload and will not restart until reset.
• Restore the breaker, run cold water, and switch it on.

If it still only hums

A jam that will not free with the hex wrench, or a unit that hums with the plate turning freely, usually means the motor or its capacitor is failing. Disposals are not economically repairable at that point — but they are inexpensive and a straightforward swap for anyone comfortable working under a sink.

Preventing the next one

• Run cold water before, during, and for about 30 seconds after grinding. Cold keeps fats solid so they get chopped rather than smeared down the drain.
• Keep fibrous material out — celery strings, corn husks, artichoke leaves wrap around the impellers rather than breaking up.
• Keep out coffee grounds, eggshells, pasta and rice: they do not jam the unit, they sludge up the trap downstream.
• Grinding a tray of ice cubes occasionally knocks buildup off the impellers.

One thing worth knowing: if water is also backing up into the sink, the disposal may not be the problem at all — a clogged trap downstream produces very similar symptoms.