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Tappan Dishwasher Not Draining

The part(s) or condition(s) listed below for the symptom Dishwasher not draining are ordered from most likely to least likely to occur. Check or test each item, starting with the items at the top of the page.

Most Frequent Causes for Dishwasher not draining

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Cause 1Clogged Sump Filters

There is usually a course and fine filter. If they are clogged, you will get low water flow and poor washability. To clean filters, remove them and wash with soap, warm water, and brush. If the filters cannot be cleaned effectively or if they are damaged, they will need to be replaced.

Cause 2Drain Pump

The drain pump uses an impeller to force water through the drain hose. If the drain pump motor is not working, the dishwasher won’t drain. To determine if the drain pump is defective, check the pump motor for continuity using a multimeter. If the motor does not have continuity, or if is getting power but won’t run, replace the drain pump. Drain pumps are not repairable—if the drain pump is defective, you must replace it.

Parts
Cause 3Control Board

A dishwasher's control board provides power to nearly every electrical component in the dishwasher. A faulty board may be unable to supply power to the drain pump, preventing it from drawing the water out of the tank and forcing it through the drain hose to the garbage disposal or sink drain pipe.

Parts
Cause 4Drain Impeller

The drain impeller pushes water through the drain hose and into the garbage disposer or drain line. If the impeller is broken, replace it.

Parts
Cause 5Drain Solenoid Kit

The drain solenoid opens the drain valve to allow the water to exit the dishwasher. If the drain solenoid fails the valve will not open causing the dishwasher not to drain.

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Cause 6Drain Valve

Over time, the drain valve can get clogged with debris. To ensure that water can flow through the drain valve, clean out the valve. If the drain valve is clear of debris but it still won’t actuate, replace it. Drain valves are not repairable—if the drain valve is defective, you must replace it.

Parts
Cause 7Main Control Board

A dishwasher's main control board provides power to nearly every electrical component in the dishwasher. A faulty board may be unable to supply power to the drain pump, preventing it from drawing the water out of the tank and forcing it through the drain hose to the garbage disposal or sink drain pipe.

Parts
Cause 8Pump and Motor Assembly

The motor drives an impeller to force water out of the drain hose. If the motor runs during the drain cycle, check for a blockage in the drain line. If the motor won't run during the drain cycle or if it just hums when it should be running, the pump and motor assembly might need to be replaced.

Parts
Cause 9Clogged or Improperly Installed Garbage Disposer

If the garbage disposer was installed recently, the drain plug may not have been removed. All garbage disposers are sold with a solid plug in the drain tube. If the dishwasher is not connected to the garbage disposer, the plug must remain in the drain tube. However, if the dishwasher is connected to the garbage disposer, the plug must be removed. If the garbage disposer wasn't replaced recently, it is possible that the disposer is clogged. Remove the dishwasher drain hose from the disposer and clean out both the fitting on the disposer and the end of the drain hose. These are the most common places to find an obstruction if the dishwasher won't drain.

Cause 10Drain Hose

The drain hose might be clogged. To unclog the drain hose, remove the drain hose from both the dishwasher and the sink drain and clean it out. The drain hose is most commonly clogged near the garbage disposer or dishwasher drain branch tailpiece.

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Cause 11Check Valve

The check valve prevents water from returning to the dishwasher after it has drained. If the valve gets stuck closed, it will prevent the water from draining. If the check valve is stuck closed, try cleaning it out and then replace it if necessary.

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Cause 12Check Ball

The check ball is a small plastic ball in the check valve that prevents water from returning to the dishwasher after the dishwasher has drained. If the check ball gets stuck, it will prevent water from draining through the check valve. If the check ball is stuck, try to free it.

Parts
Cause 13Improperly Routed Drain Hose

The drain hose needs to be connected to a siphon break or looped high under the cabinet to keep the water from siphoning back into the dishwasher. 

Cause 14Filter Assembly

A dishwasher's filter assembly usually consists of both a course and a fine filter located in the sump. If one or both of these filters is clogged, the appliance will probably not drain properly. If the filters cannot be cleaned effectively or if they are damaged, they will need to be replaced.

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Cause 15Screen Filter

A dishwasher will usually have both a course and a fine screen filter located in the sump. If one or both of these filters is clogged, the appliance will probably not drain properly. If the filters cannot be cleaned effectively or if they are damaged, they will need to be replaced.

Parts
Cause 16Strainer

Dishwashers will use a strainer located in the sump to catch food particles. If the strainer is clogged, the appliance will probably not drain properly. If the stainer cannot be cleaned effectively or is damaged, it will need to be replaced.

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