Garbage Disposal Humming or Not Working? How to Diagnose It

Safety first

The manufacturer’s instructions are clear on three things:

• Turn the disposal off before you try to clear a jam, take an object out or press the reset button. If it plugs in under the sink, unplug it too.
• Never put your fingers or hand into a disposal. Use long-handled tongs or pliers to pull things out.
• Never use chemical drain cleaners in a disposal.

Step 1: what is it doing?

Symptom	Likely cause	Go to
Hums when switched on but doesn’t spin	Something is jamming the grinding plate	Step 2
Silent, nothing at all	No power, or the overload protector tripped	Step 3
Runs, but water drains slowly	A clog below the disposal	Step 4
Leaks from the bottom or the body	Worn seals or a cracked housing	Replace it
Grinds loudly, rattles	Something hard inside, like a spoon, bottle cap or pit	Step 2 with power off

Step 2: hums but won’t spin (a jam)

This is the manufacturer’s procedure:

1. Turn off the disposal and the water.
2. Use the wrench. Find the hex hole in the centre of the disposal’s bottom. Put one end of the hex wrench that came with it (the manual calls it a self-service or Jam-Buster wrench) into the hole and work it back and forth until it turns one full revolution. Then take the wrench out.
3. Take out the object. Reach in with tongs, never your hand, and remove whatever jammed it.
4. Let it cool, then reset. Let the motor cool for 3 to 5 minutes, then push the red reset button on the bottom lightly.
5. Test it with cold water running.

Lost the wrench? Replacement hex wrenches are sold at hardware stores. Take the disposal’s model number with you.

Step 3: completely silent

1. Press the reset button on the bottom of the unit, after letting it cool for a few minutes if it just shut off.
2. Check the breaker. The manual says if the motor still won’t run, check the service panel for a tripped breaker or blown fuse.
3. Check the outlet and switch. Many disposals plug into an outlet under the sink that’s controlled by a wall switch. If that outlet is on a GFCI, reset it.
4. Still nothing? The motor or switch may have failed. If it’s hardwired and you’d need to open the electrical connection, turn off the breaker and consider calling an electrician, or replace the unit.

Step 4: runs but the sink drains slowly

The clog is usually in the trap or drain line below the disposal, not in the disposal itself. Turn off the disposal, put a bucket under the trap and clear it, or use a plunger on the sink. On a double sink, block the other drain first. See Unclog a drain.

What not to put in

The manufacturer’s list: clam or oyster shells, caustic drain cleaners, glass, china or plastic, metal (bottle caps, cans, utensils), and hot grease or other hot liquids. Run cold water while it grinds and for a little while afterwards, and leave the stopper in when it’s not in use so nothing falls in.

Repair or replace?

Replace it if it leaks from the body, if the motor won’t run with power confirmed, or if it jams constantly. A replacement of the same type may use the same mounting ring, which makes the swap easier.

Related

• Fix a garbage disposal and Garbage disposal hums or won’t turn on, videos by job and by symptom
• Sink won’t drain
• Room: Kitchen

Sources

1. InSinkErator (manufacturer instructions). Complete garbage disposal installation, care and use manual (releasing a jam, safety instructions) Source