Trash Compactor Not Compacting? Test Directional Switch

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While it’s always a good idea to look for new ways you can reduce waste, using a trash compactor to ensure that waste takes up less space is the next best option. But what do you do if your trash compactor stops working? In this week’s blog, we’ll examine how trash compactors operate and how to test the compactor’s directional switch, a component that’s critical to proper trash compactor operation.

How a trash compactor compacts

Trash compactors use an electric motor to drive one or more power screws that move a ram up-and-down within the compactor drawer. The ram will compress the trash to make it easier to dispose of provided the drawer is, at least, one-third filled.

To begin the compacting process, the drawer must be fully closed. Otherwise, the contacts in the safety switch or switches will not close which will prevent the appliance from operating. When the start switch is moved to the “start” position, 120 volts of alternating current is allowed to flow through the directional switch and energize the drive motor’s clockwise start winding and the run winding. The contacts in the centrifugal switch, located on the drive motor, will then open and the ram will move downward. The directional switch is triggered as the ram lowers and the contacts in the switch change position. Once the ram has compacted the trash, the motor slows then stalls, and the contacts in the centrifugal switch close briefly, directing current to the motor’s counter-clockwise start winding. This reverses the motor direction causing the ram to move upward. Once the ram returns to its top position, the directional switch will interrupt all current to the motor.

Be aware that many trash compactor models offer a “solid” or “hard-pack” option which keeps the ram in the down position once the trash has been compressed. Some models also have a drawer tilt switch. If the drawer is out of alignment, the contacts in the tilt switch will close, immediately returning the ram to its top position to prevent further damage to the compactor.

The relationship between the drive motor’s centrifugal switch and the directional switch is critical to compactor operation. If the appliance does not complete a compacting cycle, it’s likely the contacts inside the directional switch have become damaged.

What makes a directional switch different from other switches?

A trash compactor’s directional switch is essentially two switches assembled in one housing. The upper switch in the housing is considered a three-terminal switch. Three terminal switches will have a common terminal, usually designated by the letters “COM” on the housing, a “normally closed” terminal labeled “NC”, and a “normally open” terminal labeled “NO”. A “normally closed” terminal should provide electrical continuity (a continuous electrical path present in the switch) before the switch is actuated and a “normally open” terminal should provide continuity after the switch has been actuated. The lower switch in the housing is a simple two-terminal switch. Two-terminal switches will either have continuity before the switch is actuated or after.

Testing a trash compactor directional switch

The number one cause of a trash compactor ram continuously moving up-and-down in the drawer without stopping, or a compacting cycle not completing, is a defective directional switch. Directional switches can fail either mechanically or electrically. A damaged actuator arm is an example of a mechanical failure. To help determine if there is an electrical failure, you can use a multimeter to test the switch for electrical continuity:

  • After confirming the multimeter is properly calibrated, rotate the meter’s range selection dial to the lowest setting for Ohms of resistance.
  • Uninstall the trash compactor’s directional switch or make sure the part is isolated from the appliance’s electrical circuit.
  • To test the upper portion of the switch, connect the multimeter’s black lead to the upper switch’s “common” terminal and the red lead to the upper switch’s “normally closed” terminal (using alligator clips attached to the leads will make this easier).
  • The multimeter display should show zero Ohms of resistance, indicating the terminals have proper continuity.
  • Now depress the actuator arm – the electrical continuity should be interrupted.
  • Keeping the black lead attached to the “common” terminal, connect the red lead to the upper switch’s “normally open” terminal.
  • The multimeter display should indicate there is no continuity… until you depress the actuator arm.
  • Next, you should test the lower portion of the directional switch by connecting the meter’s black lead to the lower “common” terminal and the red lead to the lower “normally closed” terminal.
  • The multimeter display should, again, show zero Ohms of resistance, indicating the terminals have proper continuity.
  • Depress the actuator arm and the electrical continuity should be interrupted between the same two terminals.

If either an upper or lower switch terminal tests negative for continuity when it should be positive or tests positive for continuity when it should not, then the directional switch has failed electrically and will need to be replaced. If both the upper and lower portions of the directional switch pass the test, then the ram problem may be related to a malfunctioning drive motor or gear system.

Find genuine OEM trash compactor parts at Repair Clinic

If you need to replace your trash compactor’s directional switch, or any other component, you can count on Repair to provide you with a genuine OEM replacement part direct from the manufacturer, whether your trash compactor is a KitchenAid, GE, Frigidaire, Kenmore, Maytag, Roper, Broan or any other top name brand model. Enter the full model number of the compactor in the Repair Clinic website search bar to view a comprehensive list of parts compatible with the model, including the right directional switch, start switch, drive gears, motor, and foot pedal. You can then use the “Part Category” and “Part Title” navigation filters to refine that list to identify the specific part you’ll need for the repair.

As your repair partner, Repair Clinic can assist you in repairing the trash compactor yourself. Check out the “Videos & Articles” or “Repair Help” website sections to find troubleshooting and part installation videos, step-by-step guides, schematics, diagrams, and articles for the assistance you need to fix all of your home appliances, outdoor power equipment, and heating and cooling products.

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