Why Is My Dishwasher Not Cleaning Dishes?

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According to a recent survey, 73% of U.S. households have a dishwasher, even though another survey reveals that this convenient appliance often goes unused by 20% of those who own one. Okay, so maybe one in five of us prefers to wash and dry dishes by hand. But is there comfort in knowing that the dishwasher is standing by, ready to do the dishes for those times when we have better things to do? If a malfunctioning dishwasher forces us to clean the dishes ourselves, does it make the chore that much more unpleasant? Let’s agree that it’s better to have a choice and get that dishwasher back in good working order. Before you can diagnose why a dishwasher is not cleaning properly, you need to know how it works. After you learn how it works, you can troubleshoot using our advice to determine why your dishwasher is not cleaning dishes.

How a Dishwasher Works

When you select a wash cycle on your dishwasher, the control sends 120 volts of alternating current to the water inlet valve solenoid which opens the valve and allows the proper amount of water into the tub. This process will take anywhere from 90 seconds to two minutes and will usually allow around two gallons of water to fill the tub.

After the Fill Cycle Is Finished

Once the fill cycle has completed, the control sends voltage to the dishwasher circulation pump motor which uses an impeller to force water through the dishwasher’s wash arms. As the food debris is cleaned from the dishware, it collects in the sump which filters and retains the larger food particles, preventing the particles from circulating into the wash arms and, potentially, clogging them. As the water circulates through the arms, a wax motor or solenoid causes the dispenser to open and release detergent to mix with the water. Depending on the setting, the control may send voltage to a heating element periodically during the wash cycle to maintain a water temperature between 120-degrees and 160-degrees Fahrenheit.

Dishwasher Cycle Processes

After the completion of each wash cycle, the control sends voltage to the drain pump that uses an impeller to force the water through a drain hose to a garbage disposer or standpipe. The dishwasher will then go through several rinse cycles which are similar to the wash cycles and may introduce rinse aid to the water to help with drying and to reduce streaking if your home uses hard water. Following the rinse cycles, there is a final drain cycle, although some water will be left in the tub to help preserve the seals and prevent cracking. Finally, the drying cycle begins. Some models use a heating element to heat the air inside the tub while other models will rely on the heat generated by the final rinse cycle. The hot moist air will exit through a permanent vent or through a vent in the door which is opened by a wax motor or solenoid. With the drying cycle completed, the dishware is ready to be removed from the dishracks.

Top 5 Reasons Why Your Dishwasher Is Not Cleaning

So, what would cause a dishwasher to stop cleaning? Here are the top five reasons:

  1. Defective Water Inlet Valve – A clogged or defective water inlet valve will not allow enough water into the tub to clean the dishware properly, which could be why the dishwasher is not cleaning well. To help determine this, pour one to two quarts of water into the bottom of the tub and run the dishwasher. If the wash performance improves, the valve is probably restricted and should be replaced. Trying to clean out an old valve is not recommended since the damage caused by the initial restriction puts the part at a greater risk for failure in the future, which could lead to a leaking dishwasher.
  2. Clogged Wash Arm – Over time, food particles can clog the tiny holes in the wash arm, obstructing the water flow. You should use a small brush or pipe cleaner to clean out the debris as part of your regular dishwasher maintenance.
  3. Damaged Wash Arm Support – On most dishwasher models, the water reaches the wash arms through a support tube. A damaged support may be unable to mate properly with the supply tube nozzle, obstructing the water, and causing the dishwasher to not clean dishes. For some models, the support can be replaced separately from the arm, but you may need to purchase an entire wash arm assembly to fix the problem.
  4. Broken Impeller – A broken circulation pump impeller may not be able to generate enough pressure to drive the water. Depending on the model, you may be able to replace the dishwasher impeller independently of the circulation pump motor.
  5. Faulty Circulation Pump Motor – If the circulation pump motor doesn’t make any noise during operation, or just hums after the tub has been filled with water, then the component has probably burned out. You will need to replace the pump motor with a new one before your dishwasher will be able to start cleaning again.

Find the Right Dishwasher Parts with Repair Clinic

If your dishwasher is not cleaning dishes, Repair Clinic stocks all the replacement parts you need to repair or maintain your dishwasher, including drain hoses, water inlet valves, drain pumps, circulation pump motors, wash arms, dishracks, heating elements, and much more. To get started, you’ll need to identify the dishwasher’s model number which can be found on a label attached to the top or side of the dishwasher door. Enter the full model number of the appliance in the Repair Clinic website search bar for a complete list of compatible parts. Repair Clinic carries parts for all the top brand dishwashers including Bosch, KitchenAid, Kenmore, Maytag, Samsung, GE, Frigidaire, LG, and Whirlpool dishwasher replacement parts, but you’ll need to make sure you’re purchasing the right part for it to work with your model.

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