Garbage Disposer Won’t Turn On? 3 Likely Causes

Home » Garbage Disposer Won’t Turn On? 3 Likely Causes

You would think we would all agree by now whether that little appliance hidden under the kitchen sink should be called a garbage “disposer” or a garbage “disposal”. But if the internet can be trusted to be an accurate reflection of public consensus (don’t answer that!), the jury is most definitely still out on the accepted terminology. While the words “disposer” and “disposal” may be interchangeable, there are actually two distinct types of these units that should be identified by different monikers: “continuous-feed” garbage disposers (or disposals) and “batch-feed” disposals (or disposers).

“Continuous-feed” disposers vs. “batch-feed” disposers

If you haven’t already noticed, we favor the word “disposer” and to keep things simple, that’s the term we’ll be using from this point on. Not all garbage disposers operate in the same way. The more commonly installed units are known as “continuous-feed” disposers. These units are usually hard-wired to a wall switch near the sink, and you can continuously insert food waste while the disposer is running (provided a steady stream of cold water continues to flow through the unit at the same time).

“Batch-feed” disposers require the food waste to be inserted before turning the unit on. The disposer gets its name because the waste is being inserted in batches (depending on the model, the size of the “batch” can range from three to five cups of food particles). Once the food waste is inserted, a cover or stopper is positioned in the drain opening and is pushed down and/or rotated. This action actuates a start switch on the top of the unit which allows 120 volts of alternating current to flow to the disposer’s motor. The motor then rotates a grinding, or shredder, plate to break down the food waste.

While not as popular as “continuous-feed” disposers, there are a number of reasons homeowners would choose a “batch-feed” unit instead. These include both safer and quieter operation, as well as easier installation.

Why won’t the “batch-feed” disposer turn on?

If you have a “continuous-feed” disposer that won’t turn on, it’s likely that something is wrong with the wall switch or the incoming power to that switch, although the disposer’s motor could be burned out as well. The failure of a “batch-feed” disposer to turn on may be the result of something different. Here are the three most likely causes for why a “batch-feed” disposer won’t turn on and how you can determine the correct cause of your unit’s malfunction:

  1. Defective start switch – As noted above, when a “batch-feed” disposer stopper is pushed down/rotated, it activates a start switch to run the appliance. If the start switch is defective, the disposer won’t turn on. You should first check to see if a house fuse has blown, or a circuit breaker has tripped. If you’ve determined the disposer should be receiving power, you can use a multimeter to test the start switch for continuity – a continuous electrical path present in the switch. If the switch tests positive for continuity, it should be functioning properly. However, if the switch tests negative for continuity, it is definitely defective and will need to be replaced.
  2. Faulty stopper – If you’ve determined the start switch is functioning normally, then the next most likely cause of the disposer not turning on is a faulty stopper. Fortunately, a new stopper can be relatively inexpensive and easy to replace.
  3. Worn-out motor – If the stopper appears to be undamaged, then it’s likely the motor has simply worn-out. Since the motor is not replaceable on its own (and unlikely to be repairable), you will need to replace the old disposer with a new one to solve the problem.

Bonus troubleshooting tips

It’s possible the disposer’s grinding, or shredder, the plate is jammed, making it appear as if the unit is not turning on. The plate will often jam if fibrous food materials such as potato peels, corn husks, or celery are inserted into the unit (we recommend depositing fibrous food waste directly into the trash bin). To unclog the unit, you can often insert an appropriate-size Allen wrench into the opening on the bottom of the disposer housing and rotate the wrench back-and-forth. If your model doesn’t have an opening on the bottom of the housing, a wooden broom handle can be inserted through the sink drain opening to turn the plate in order to clear the obstruction.

Some garbage disposers will have a safety switch that will shut the power off to the motor if the grinding plate jams (this is to protect the motor). Once you confirm the plate can rotate freely, press the red reset button on the side or bottom of the unit to restore the power. If you’re still unable to get the disposer to work, it’s possible the safety switch is defective. As with the start switch, you can use a multimeter to test the component for electrical continuity to determine if the part has failed.

Keep your disposer working with the right part from Repair Clinic

Whether you need to replace the start switch, stopper, or a flange gasket, splash guard, or any other garbage disposer component, Repair stocks genuine manufacturer replacement parts for units built by such top brands as Kenmore, Emerson, Frigidaire, GE, Whirlpool, Insinkerator, Sinkmaster, Waste King, and Whirlaway. How can you find the right part for your particular unit? Enter the full model number of the garbage disposer in the Repair Clinic website search bar to see a complete list of compatible parts. From there, you can use the “Part Category” filter (Examples: “Switch”, “Cap, Lid & Cover”) followed by the “Part Title” filter (Examples: “Start Switch”, “Stopper”) to identify the specific part that matches your disposer.

In addition to millions of replacement parts, Repair Clinic is home to a comprehensive library of DIY repair help content. With a little exploring, you’ll discover thousands of troubleshooting and “how-to” videos, diagrams, schematics, and step-by-step guides; all created to assist you in taking on the repair yourself. You’ll gain the confidence you need to fix your own appliances, outdoor power equipment, and heating and cooling products, while saving money with every repair.

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