Dishwasher Not Cleaning Dishes? How to Fix It

Paradise Appliance
April 1, 2022
Dishwasher Repair

There are numerous reasons your dishwasher may not be sufficiently cleaning the dishes. If you are lucky, it could just mean adding Rinse Aid or cleaning the filter. In other cases, the fix can be slightly more difficult, such as accessing and testing the circulation pump with a multimeter. Fortunately, you have this guide to take you through the most common reasons the dishwasher is not washing properly, with instructions for how you can fix the issue.

1. Defective spray arms

Dishwasher spray arms are an important part of how the dishwasher cleans dishes. If a spray arm can not spin during a wash cycle, the dishes will not clean properly, and a damaged spray arm or blocked hole on the spray arm will also restrict the dishwasher’s ability to clean the dishes.

You may need to remove the spray arms from the dishwasher to unblock and clean them. A pipe cleaner or wire brush can be used to unblock the spray arm holes, and the spray arms can be cleaned with dish soap and warm water. If debris is caked-on, soak the spray arms in white vinegar or baking soda, and then clean with a scrubbing brush.

Follow these steps to check the spray arms:

  1. Check that the spray arms are not being obstructed.
  2. Check the spray arms for signs of damage and blockages.
  3. Unblock and clean off any debris blocking the spray arm holes.
  4. Replace a damaged spray arm.

2. Clogged wash arm manifold (wash arm assembly)

Depending on the type of dishwasher, it may have a manifold that supplies water from the pump to the upper spray arm (sometimes the middle spray arm as well).

If it seems like weak water pressure from the spray arms is responsible for the dishes not being clean, and you have checked and cleaned the spray arms, the wash arm manifold may be clogged or not aligned correctly. However, a problem with the circulation pump could also be causing this issue (see below).

Depending on the dishwasher, the wash arm manifold may be attached to a dish rack or an inner panel of the dishwasher. Some dishwashers may require the removal of the dishwasher’s kickplate or sump assembly to access the manifold.

Follow these steps to check the wash arm manifold:

  1. Check if your dishwasher has a wash arm manifold.
  2. Turn off the power and water to the dishwasher.
  3. Remove the wash arm manifold.
  4. Run water through the manifold to unclog it. If it has a filter attached, clean out the filter.
  5. Make sure the manifold aligns correctly with the spray arms.

3. Not using rinse aid

If you are not using Rinse Aid in your dishwasher, that could be the reason your dishwasher is not cleaning the dishes. Rinse aid lowers the surface tension of water, which helps prevent water spots from forming and cloudy stains caused by hard water. Rinse aid also helps the dishes to dry faster.

The dishwasher’s Rinse Aid dispenser will add Rinse Aid to the wash when it will be most effective. While dishwasher detergent tablets may have Rinse Aid in them, it will not assist the wash as well as adding Rinse Aid yourself.

4. Water temperature

The dishwasher requires a water temperature of 120 degrees Fahrenheit to effectively clean the dishes (do not exceed 140℉). If the water temperature is too low, carefully adjust the water temperature on your water heater (for safety, only make small adjustments).

Follow these steps to test the water temperature:

  1. Run the hot water in the kitchen for one minute.
  2. Fill a cup with hot water.
  3. Use a cooking thermometer to check the water temperature.

Alternatively, you could let the dishwasher fill and then pause the dishwasher and measure the temperature in the dishwasher basin.

5. Detergent dispenser

If the dishwasher detergent dispenser is broken, the dishwasher detergent may be dissolving too fast, being prematurely drained out of the dishwasher, or not entering the dishwasher at all.

A dishwasher detergent dispenser that has caked-on detergent or residue can also affect the dishwasher’s ability to clean.

Follow these steps to check the detergent dispenser:

  1. Check that the detergent dispenser lid can open and close. If the lid is stuck or loosely staying shut, either the latch or the dispenser should be replaced.
  2. If the dispenser has detergent residue, clean the dispenser with a dish brush and either dish soap, white vinegar, or baking soda.
  3. Make sure the dispenser is clean before adding detergent. If your detergent is not dissolving, either change the detergent, reduce the amount, or consider replacing the dispenser to fix the problem.

6. Dirty filter and chopping assembly

Most dishwashers have a filter and chopping assembly beneath the bottom spray arm and dishrack. If the filter is clogged or the chopping blade is defective, it could be hindering the wash cycle. Note that depending on the dishwasher, the chopping blade assembly may be difficult to access.

Follow these steps to check the filter and chopping blade assembly:

  1. For safety, turn off the power to the dishwasher.
  2. Remove the bottom dish rack and spray arm.
  3. Locate the filter and turn it counterclockwise to remove it.
  4. Clean the filter with dish soap and a dish brush.
  5. Remove the screws that secure the lower wash arm support and filter assembly, and remove it from the dishwasher.
  6. Remove the foreign object protector and the pump inlet protector by removing their screws.
  7. You should now have access to the chopping blade and can check it for debris or signs that it needs to be replaced.

7. Defective Water Inlet Valve

The water inlet valve opens and closes to allow water into the dishwasher. If the valve is defective, it could be preventing enough water or water pressure to effectively clean the dishes.

Follow these steps to check the water inlet valve:

  1. Turn off the power and water to the dishwasher.
  2. Remove the dishwasher’s kickplate.
  3. Locate the water inlet valve and remove it from the dishwasher.
  4. Check the water inlet valve for continuity with a multimeter.
  5. If the valve does not have continuity, it will need to be replaced.
  6. If the valve is worn or clogged, it should be replaced rather than trying to repair it.

8. Defective Circulation Pump

Most dishwashers have a circulation pump, as well as a drain pump. Depending on the type of dishwasher, the circulation pump is responsible for supplying water to the spray arms during a wash and rinse cycle. If the pump is defective, the dishwasher may not be getting enough water or water pressure to wash the dishes properly. With most dishwashers, the dishwasher will need to be moved and put on its back to access the pump underneath the dishwasher (check the manual for pump access instructions).

Follow these steps to check the circulation pump:

  1. Turn off the water and power to the dishwasher.
  2. Access the circulation pump.
  3. Check that the impeller can turn freely and is not damaged.
  4. Remove any debris that is clogging the pump.
  5. Remove the pump from the dishwasher and test the pump for continuity with a multimeter. If the pump fails the test, it will need to be replaced.

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