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Garbage Disposers

The garbage disposer provides a convenient and sanitary way to dispose of food waste

(Figure 15-1). No sorting or separating of the food waste is necessary. It is designed to

handle all types of food waste. If, however, the garbage disposer drains into a septic

tank, organic wastes, such as egg shells, lobster, crab, and shrimp shells should be kept at a

minimum. Items such as tin cans, glass, china, bottle caps, metal, etc., should never be placed

in the garbage disposer because they might damage the appliance and plug the drain.


There are two types of operating methods available in garbage disposers: continuous feed

and batch feed.

Continuous Feed Disposers

A continuous feed disposer requires an on-off electrical switch that is remote from the

disposer. Before food is placed into the hopper, the user must turn on the cold water faucet

and turn on the electrical switch. Then the food waste is placed into the hopper. The food

waste will be ground up and expelled into the drain.

Batch Feed Disposers

In a batch feed disposer, the on-off operation of the disposer is controlled by the stopper.

The on-off switch is built into the hopper. The stopper is the component that completes the

circuit that allows the disposer motor to run. The hopper will hold the food waste until the

user is ready to dispose of it. The food waste will be ground up and expelled into the drain.

Principles of Operation

When the food is placed into the hopper and the disposer is running, the centrifugal force

throws the food waste outward against the cutting edges of the shredder ring (Figure 15-2).

The pivoting impeller arms, attached to the flywheel, push the food waste around and

into the teeth of the shredder ring (Figure 15-3). As the food waste is pushed against and

cut by the shredder ring, water running into the hopper flushes the ground food waste

between the flywheel and the shredder ring, washing it into the drain housing assembly,

where it is expelled into the drain.



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Inspection plate

Retaining ring

Overload protector



Bowed washer

Start switch

Switch screw

Motor housing

Drain housing


Water seal

Hopper gasket




Shredder stop



Seal spacer


Washer thrust

Rotor assembly

Fiberboard barrier

End bell

Motor bolt


FIGURE 15-1 Exploded view of a batch feed garbage disposer.

FIGURE 15-2 Food waste is forced outward

against the shredder ring.

FIGURE 15-3 Impeller directing food waste

into the teeth of the shredder ring.


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Safety First

Any person who cannot use basic tools or follow written instructions should not attempt to

install, maintain, or repair any garbage disposers. Any improper installation, preventive

maintenance, or repairs could create a risk of personal injury or property damage.

If you do not fully understand the installation, preventive maintenance, or repair

procedures in this chapter, or if you doubt your ability to complete the task on the garbage

disposer, call your service manager.

These precautions should also be followed:

Do not put your fingers or hands into the garbage disposer.

When removing foreign objects, always use a long-handled pair of tongs or pliers.

To reduce the risk of flying debris that can be expelled by the disposer, always be

sure that the splash guard is properly installed.

When replacing the garbage disposer, always be sure that it is properly grounded.

Before attempting to free a jam in the garbage disposer, always disconnect the

electric supply to the disposer.

Garbage Disposers in General

Much of the troubleshooting information in this chapter covers the various types of garbage

disposers in general, rather than specific models, in order to present a broad overview of

service techniques. The pictures and illustrations that are used in this chapter are for

demonstration purposes only, to clarify the description of how to service these units, and in

no way reflect on a particular brand’s reliability.

To Free Jams from Foreign Objects

When foreign material falls into the disposer and the motor jams, it will trip the motor

overload protector—otherwise known as the reset button (see Figure 15-1). When this

happens, follow these steps to free the jam:

1. Turn off the electricity to the disposer, and shut off the water.

2. Insert the service wrench into the center hole at the bottom of the disposer

(Figure 15-4), and work the wrench back and forth until the motor assembly is

turning freely.

3. To free a tight jam, insert a prying tool alongside the grinding protrusion near the

outside edge of the flywheel. Be sure that you place the prying tool on the proper

side of the protrusion so that when pressure is applied, the flywheel will move

(Figure 15-5).

4. Remove the foreign object with tongs.

5. Wait for the motor to cool for a few minutes before you press the reset button.

6. Reconnect the electric supply, turn on the cold water, and test the disposer.

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Installation of Garbage Disposer

Figure 15-6 shows some typical installations of garbage disposers. Every newly purchased

garbage disposer comes with installation instructions, a use and care manual, and a

warranty. The steps taken to install a new disposer are as follows:

1. Read the use and care manual.

2. Clean out the sink’s drain line.

3. Disconnect the electrical supply:

a. Continuous feed disposers need a wall switch and a receptacle.

b. Batch feed disposers need a receptacle or must be wired directly.

4. Be sure to observe all local codes and ordinances for electrical and plumbing

connections when installing or repairing disposers.

5. Follow the manufacturer’s installation instructions.

6. After completing the installation, check for water leaks.

7. Turn on the electricity, and test the operation of the garbage disposer.

Garbage Disposer Maintenance

The garbage disposer is permanently lubricated; thus, it never has to be oiled. When the

disposer is used properly, it cleans itself. If there is an odor coming from the inside of the

disposer, you can deodorize it. To do this, take some orange or lemon rinds and grind them

up in the disposer. This will dispel unpleasant odors and leave the sink with a sweet smell.

Another way to deodorize the disposer is to take about a dozen or so ice cubes sprinkled

with a generous amount of household scouring power and grind them up in the disposer



FIGURE 15-4 Insert service wrench, turn

wrench, and reset the overload protector


FIGURE 15-5 Insert prying tool into the



splash guard


broom or

mop handle




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without running the water. Flush the disposer for one minute. This will allow any debris to

be expelled into the drain.

Drain Blockage

To avoid drain blockage when using the garbage disposer, allow the cold water to flow for a

sufficient time after grinding the food waste to be sure that all of the waste is flushed away.

The ground waste and water mixture flows at the rate of two seconds per foot in a horizontal

drain line. It is recommended that the user allow the water to flow for a minimum of 15 to

30 seconds after grinding the food waste.

The use of cold water in the garbage disposer will congeal and harden the grease,

making its disposal easier. Never use chemicals or solvent drain compounds, because they

can cause serious damage to the disposer.

The disposer should be used daily to flush the lines. If the dishwasher drain hose is

connected to the disposer, it, too, should be used daily to prevent the dishwasher drain hose

from becoming clogged.

Double bowl center outlet

Double bowl end outlet

Single bowl


Typical garbage

disposer installations.

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Step-by-Step Troubleshooting by Symptom Diagnosis

In the course of servicing an appliance, don’t tend to overlook the simple things that might

be causing the problem. Step-by-step troubleshooting by symptom diagnosis is based on

diagnosing malfunctions, with their possible causes arranged into categories relating to the

operation of the garbage disposer. This section is intended only to serve as a checklist to aid

you in diagnosing a problem. Look at the symptom that best describes the problem you are

experiencing with the garbage disposer, and then proceed to correct the problem.

Overload Protector Trips

1. Check for voltage at the garbage disposer.

2. Does the motor hum when the disposer is turned on?

3. Was the foreign material removed from the hopper? Make sure that the flywheel

turns easily.

4. Does the motor stay in the start winding? Use the ammeter to perform this check.

Look at the name plate for the correct amperage rating.

5. Did you check the overload protector?

6. Is there a shorted or open winding in the motor?

7. Is the start relay okay?

Erratic Operation

1. Are there any loose connections? For example: wiring, switch, motor, etc.

2. Is the stopper worn or broken?

3. Is the wall switch defective?

4. Is the garbage disposer wired correctly?

Garbage Disposer Won’t Run

1. Did the overload protector trip?

2. Is the fuse or circuit breaker blown or tripped?

3. Is the wall switch okay?

4. Are the motor windings burned out?

5. Check for open or shorted wiring.

6. Is the relay defective?

Garbage Disposer Won’t Stop

1. Is the wall switch defective?

2. Check for a short in the wiring.

3. Check for incorrect wiring.


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Slow Water Flow from Garbage Disposer

1. Check to see if the drain is partially clogged.

2. Check the shredder teeth, and see if they are clogged with food waste. This is

caused by insufficient water flow.

Garbage Disposer Is Grinding Slowly

1. Check for undisposable matter in the hopper.

2. Is the flywheel damaged?

3. Is there sufficient water flow?

4. Is the shredder ring worn or broken?

Abnormal Noise in the Garbage Disposer

1. Check for undisposable matter in the hopper.

2. Are the mounting screws loose?

3. Is the flywheel broken?

4. Check the motor bearings—they might be damaged or worn.

Garbage Disposer Leaks

1. Disconnect the electricity. Then locate the water leak.

2. Check for loose mounting screws.

3. Check the sink flange. There might be insufficient putty around the flange.

4. Check for leaks around the tail pipe gasket.

5. Check for holes in the hopper.

6. Is the dishwasher/disposer connector cracked and leaking?

7. Is water leaking through the motor assembly? The seals might be faulty.

Repair Procedure

The repair procedure in this chapter is a complete inspection and repair process for the

garbage disposer components. It contains the information you need to test a component that

might be faulty and to replace it, if necessary.

Garbage Disposer Assembly

The typical complaints associated with garbage disposer failure are:

When the motor runs, there are loud noises.

Water is leaking from the bottom of the disposer.

The fuses or circuit breaker will trip when the disposer is started.

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To handle this problem, perform the following steps:

1. Verify the complaint. Verify the complaint by operating the disposer. Listen carefully,

and you will hear if there are any unusual noises or if the overload protector trips.

2. Check for external factors. You must check for external factors not associated with

the garbage disposer. Is the disposer installed properly? Does the disposer have the

correct voltage?

3. Disconnect the electricity. Before working on the garbage disposer, disconnect

the electricity. This can be done by pulling the plug out of the wall receptacle. Be

sure that you only remove the disposer plug. Or disconnect the electricity at the

fuse panel or at the circuit breaker panel. Turn off the electricity. The voltage at

the receptacle is between 108 volts and 132 volts during a load on the circuit. Do

you have the correct polarity? (See Chapter 6.)

4. Remove the garbage disposer. To access the disposer assembly, the disposer must

be removed. Start by disconnecting the drain line from the disposer discharge tube.

Next, remove the dishwasher drain hose connection, if so equipped (Figure 15-7a).

Insert the service wrench into the right side of the flange body.

CAUT ION Place one hand under the disposer to keep it from falling.

5. Now, turn the flange to the left to free the disposer from its mounting (Figure 15-7b).

Turn the disposer upside down, and place it on a protective surface. This will protect

the floor in the cabinet from damage. Remove the terminal plate (Figure 15-7c).

Remove the ground wire and wire nuts from the service cord (Figures 15-7d and

15-7f). Separate the service cord wires from the motor wires. On models that are

wired directly, loosen the cable clamp screws and remove the cable from the disposer

(Figure 15-7e).

6. Disassemble the garbage disposer. Place the garbage disposer upside down on a

protective surface or on a workbench. Some models have an insulated outer shell

that must be removed first. Most disposers will separate into four or five sections,

depending on the model you are servicing.

Disposers that separate into four sections consist of:

Top container or hopper body

Upper-end bell or drain, housing assembly, cutting elements, and rotor and shaft



Lower-end bell assembly

Disposers that separate into five sections consist of:

Top container or hopper assembly

Stationary shredder

Upper-end bell or drain, housing assembly, rotor shredder, and rotor and shaft



Lower-end bell assembly


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Drain line


drain hose

(a) (b)



Wire nuts

Green ground


Cable clamp



Wire nuts

Green ground


Cable clamp

Wire nuts



G Ground screw

FIGURE 15-7 The steps taken to remove the garbage disposer.

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Before removing any screws from the disposer, you must place scribe marks on the

lower-end bell and stator, the upper-end bell and stator, and the upper-end bell and

hopper. These scribe marks will be used to align the sections properly when the

garbage disposer is reassembled. Remove the four through-bolts from the lowerend

bell assembly, and separate the sections of the disposer. Label the wires from

the stator to the lower-end bell assembly. Disconnect them. Be cautious if the

garbage disposer has a capacitor.

WARNING Do not touch capacitor terminals. A charged capacitor can cause severe shock when both

terminals are touched. A charged capacitor will hold a charge until it is discharged.

7. Inspect and test the garbage disposer components. Inspect the hopper assembly

for cracks, holes, and (on some models) corrosion around the dishwasher

connection. Also inspect the gasket area for nicks or rough spots. Inspect the gasket

or “O” ring for cuts, breaks, or worn areas.

Replace any defective parts. Inspect the upper-end bell or drain housing assembly for

defective parts. Test the centrifugal switch for binding by manually operating it. It

should slide up and down freely. Inspect the rotor and thrust washer for cracks,

breaks, or wear. If the upper drain housing and rotor assembly fail inspection,

replace the garbage disposer as a complete unit.

Before testing the capacitor, it must be discharged. Use a screwdriver with an

insulated handle. Discharge the capacitor by shorting across both terminals. Remove

the wire leads, one at a time, with a pair of needle nose pliers. Set the ohmmeter

on the highest scale, place one probe on one terminal, and then attach the other probe

to the other terminal (Figure 15-8).

Observe the meter action. While the capacitor is charging, the ohmmeter will dip

toward zero ohms for a short period of time. Then the ohmmeter reading will


6 8 10 15 20 30 50 100


5 4 3 2 1 0






7 10 15 20

5 4 2 3 1 0

30 50 100 200500






































6 4 2 0 2 4 6










L P ( )














L P ( )











150 VDC



5A 50mA

25 0mV


FIGURE 15-8 Place ohmmeter test leads on the capacitor terminals.


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return to infinity. If the ohmmeter reading deflects to zero and does not return to

infinity, the capacitor is shorted and should be replaced.

If the ohmmeter reading remains at infinity, the capacitor is open and should be

replaced. Another way to test the capacitor is to use a capacitor tester.

Inspect the stator windings for nicks, cuts, or burned spots. Set the ohmmeter on R × 1,

and test the stator windings for open, grounded, or shorted windings. Test both the

start and run windings. If the start or windings fail the test, replace the garbage

disposer as a complete unit. Set the ohmmeter on R × 1, and test the start switch.

Place the probes on the wires leading to the switch. To ensure an accurate meter

reading, isolate the start switch wires from the remainder of the circuitry. The

meter reading will indicate an open circuit. If the test fails, replace the start switch.

Next, test the overload protector. Isolate the overload protector wires from the

remainder of the circuitry. Then place the ohmmeter probes on the overload

protector wires. Push the red reset button on the overload protector. The ohmmeter

reading will indicate a closed circuit. If this test fails, replace the overload protector.

8. Reassemble and reinstall the garbage disposer. To reassemble the disposer, just

reverse the disassembly procedure, and reassemble. Check to be sure that all

wiring is correct. Remember to use the scribe marks to align the sections properly

before inserting the through-bolts. Also, be careful not to damage any of the gaskets

or “O” rings when assembling the garbage disposer. Reconnect the service cord

wires to the motor wires, and tighten the cable clamp screws (see Figure 15-7e).

Next, reconnect the ground wire to the green ground screw (see Figures 15-7d and

15-7f). Reinstall the terminal plate and screw (Figure 15-9a).

Lift the disposer, and position it so that its three mounting ears are lined up under the

ends of the sink mounting assembly screws (Figures 15-9b and 15-9c). The disposer will

now hang by itself. After the plumbing is reconnected, tighten the ring using the service

wrench. Rotate the disposer to align the discharge tube with the drain trap (Figure 15-9d).

Reconnect them. Next, reconnect the dishwasher drain hose connection, if so equipped

(Figure 15-9e). Finally, place the service wrench into the left side of one of the disposer

mounting lugs, located on the top of the disposer. Then turn the wrench to the right until it

is firmly secured, engaging the locking notch (Figure 15-9f).

Before you reconnect the electricity, check for leaks by running the water. Inspect all

connections. Inspect the disposer for water leaks also. If no leaks are present, turn on the

electricity and run the disposer; reinspect for any water leaks.

Before installing a new garbage disposer, the dishwasher connection plug must be

removed if the defective disposer was equipped with a dishwasher drain hose connection.

The dishwasher connection plug is removed by knocking the plug out with a hammer and

some blunt instrument, such as a dowel or a punch (Figure 15-10). Do not use a screwdriver

or any sharp tool. This can be driven through the plug and make it difficult to remove.

Remove the plug from the hopper before installing or operating the disposer.