Garage Disposal Not Working? It Could Be A Jammed Shaft

Kitchen sink garbage disposals are one of the modern conveniences that make food preparation a lot easier. When they malfunction, it is frustrating and messy for homeowners trying to accommodate. Fortunately, a common and easily-corrected disposal problem is a jammed motor shaft, and it is something you can often resolve yourself. Below are a couple of common repairs to try before calling a plumber or attempting to replace the unit:

The problem explained and some solutions to try

In the typical garbage disposal unit, the electric motor lies at the bottom and has an output shaft proceeding vertically into the grinding chamber. The shaft is attached to a rotating cutting disc which cuts food scraps are cut into fragments.

If food or a foreign object becomes wedged into a fixed position inside the grinding chamber, it can bind the cutting disc which also prevents the motor shaft from turning. This leads to a couple of problems, both of which are addressed below:

Tripped thermal overload switch

A thermal overload is common in situations where a garbage disposal is jammed; as the motor attempts to turn but can't, the electrical current feeding it cannot be utilized for useful work. Therefore, this excess current is dissipated as heat energy which can burn out the wiring inside the motor or even cause a fire in rare instances.

Fortunately, most garbage disposal motors are equipped with thermal overload switches. This switch contains a thermostat that will cut power to the motor if a certain temperature threshold in the wiring or close proximity is exceeded.

Besides a jammed motor shaft, one other thing can also cause a thermal overload switch to trip: running hot water while using the disposal. As a result, most manufacturers recommend using cold water only to prevent this from happening.

In most instances, the thermal overload switch can be manually reset by the user. Look at the bottom of your garbage disposal for a small round, red button approximately one-quarter of an inch in diameter. You may need a flashlight to see it if it is dark underneath the sink. Push the reset button one time, and then attempt to restart your disposal. If the disposal doesn't start running immediately, or if you hear a humming sound, turn off the switch as there is likely still a jam inside the grinding chamber.

Jammed motor shaft

If pushing the reset button doesn't enable your garbage disposal to be turned-on again, then the next step is to clear a possible jam inside the unit's grinding chamber.

Most garbage disposals are constructed with a manual interface for turning the motor shaft by hand in order to clear jams. This interface consists of a hexagonal-shaped socket at the end of the motor shaft, and you can also access this component from the bottom of the disposal. The socket will be in the center of the disposal, though it may be recessed inside the disposal a few fractions of an inch.

Some garbage disposals come with a hex-key, also known as an Allen wrench, designed to fit this socket. However, if you aren't able to locate your hex-key or the unit didn't include one, a standard set of hex-keys will contain the size you need. Simply insert hex-keys until you find the one that fits snugly in the socket.

Once you have found the proper-sized hex-key , the next step is to insert it into the socket and firmly turn it approximately one-quarter turn in each direction. If you feel resistance, keep turning. After turning it back-and-forth several times, attempt to turn the motor shaft a full revolution. If you feel it spinning freely without any noise or undue resistance, then you have dislodged the jam.

Remove the key, turn on running cold water, and flip the garbage disposal switch. If that fails to turn-on the unit, then press the reset button once more before turning on the disposal switch.


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