Garbage Disposal Humming but Not Working? Causes and Fixes

A garbage disposal that hums but does not grind has power reaching the motor, and the motor cannot turn the grinding plate. The hum is the sound of a motor straining against something stuck. The 4 common causes are a jammed flywheel, a hard object lodged in the chamber, a tripped overload protector, and a worn-out motor. Switch the disposal off as soon as the hum starts, because a straining motor overheats within seconds. Never reach into the disposal chamber with a hand.

Is the disposal jammed by a hard object?

Yes, a jam is the most common cause of a humming disposal, and the jam usually comes from a bottle cap, a bone fragment, a utensil, or a piece of glass that slipped into the chamber. The object wedges between the grinding plate and the chamber wall, and the plate cannot rotate. The check is visual and hands-off: with the switch off, shine a flashlight into the chamber and look for a foreign object. An object that is visible can come out with tongs or needle-nose pliers — never fingers. After removal, the plate should turn freely.

How does the flywheel get freed by hand?

The flywheel can be turned by hand with a hex wrench (Allen key) in the socket at the bottom center of the disposal, with the power switch off. Most disposals have a hex socket under the unit. Insert a 1/4-inch hex wrench and work the wrench back and forth. The motion rotates the plate manually and usually dislodges the jam. Run cold water and switch the disposal on briefly afterward to flush the loosened material into the drain line. A disposal that drains poorly even after the jam clears may have a clog past the chamber, covered by the kitchen sink unclogging service page.

What does the red reset button do?

The red reset button is the overload protector, and the protector cuts power to the motor when the motor strains or overheats. The button sits on the bottom or lower side of the unit. A disposal that hummed and then went silent has often tripped the protector. Wait several minutes for the motor to cool, press the reset button, run cold water, and switch the disposal on. A protector that trips again on an empty chamber points to a motor problem rather than a jam.

When is the motor itself the problem?

The motor is the problem when the chamber is clear, the flywheel turns freely by wrench, the reset button is pressed, and the disposal still hums or stays dead. Bearings wear and motor windings fail with age and heavy use. A dead motor is not a drain problem and not a jam problem; the unit itself needs replacement. Water leaking from the bottom of the unit at the same time points the same way — the internal seals have failed. Leak sources under the cabinet are covered in kitchen sink leaking under the cabinet.

Frequently Asked Questions