Dishwasher Not Cleaning Top Rack? How to Fix It

VIA Appliance
November 6, 2023
Dishwasher Repair

Dishwashers are truly a marvel of modern home appliances! They save a ton of time, wash your dishes better than you ever could by hand, and actually use less water than handwashing! So when your trusty dishwasher isn’t working correctly, it’s a pretty frustrating experience. 

If you find that your dishwasher appears to be functioning normally, but the dishes on the top rack just aren’t getting as clean as they should, don’t panic! There are some pretty common causes that have relatively simple solutions – even for a novice DIYer! Read on to find out what to do!

Low Water Pressure

For your dishwasher to work optimally, it needs to have a certain amount of water pressure so that the jets inside can reach the top rack. If your dishwasher seems to be functioning correctly, but the top rack is consistently not getting clean, water pressure could be the issue. 

If you’ve noticed this issue is happening intermittently with your dishwasher, check to see if it occurs when other water-consuming appliances are being used. If the top rack only stays dirty when another appliance, such as the washing machine, is being used or when someone is taking a shower, a simple solution could be to ensure you only run the dishwasher when nothing else is running. You could try getting into a routine of putting it on before you go to bed when no other appliances are being used. 

If the issue happens every time the dishwasher is put on, regardless of other water use, then the water pressure to the dishwasher itself could be to blame. To check this:

  • Turn off the water supply to ensure you don’t have any accidental floods.
  • Locate the water supply valve. If you’re unsure where it is, refer to your user’s manual. 
  • Open up the water supply valve and check to ensure it is turned on the whole way. If it isn’t, turn it up to its maximum, then turn the water back on and rerun the dishwasher. If low water pressure was the culprit, the top rack should now be cleaned properly. 

Overloaded Dishwasher

An overloaded dishwasher is a surprisingly common cause of your top rack not cleaning properly! If the dishwasher is crammed full of dishes, there may not be enough space between the items to let the water jets clean them properly. Too many big, heavy items on the bottom rack can even impede the upper spray arm from doing its job. 

To fix this:

  • Look at your dishwasher manual to ensure you’re following loading guidelines. Larger, taller items should always be on the bottom rack but not so tall that they touch the upper rack. 
  • Ensure that your plates and saucers are not jammed too tightly together. Remember, if you can’t see a gap between them, it’s pretty likely water can’t clean between them either!
  • Make sure you’re using the correct wash schedule for how full your dishwasher is. Some dishwashers can choose a half load, and if you accidentally have that setting engaged, your dishwasher may just be washing the bottom rack. 
  • If you have a lot of dishes, remember that it’s better to run two loads that both get perfectly clean than it is to run an overfilled load!

Upper Spray Arm Is Obstructed

The dishes on the top rack are cleaned by the upper spray arm, located on the underside of the top rack. When it spins, jets of water shoot upwards toward the dishes on the top rack, cleaning them thoroughly. However, if the top spray arm is obstructed in some way and prevented from spinning, then those top rack dishes won’t get properly washed. 

To fix this:

  • First, check to make sure the upper spray arm can properly rotate. It can be blocked by a large item on the bottom rack or something sticking downwards from the top rack. Rotate the upper spray arm manually with your hand – it should turn very easily. 
  • Remove anything blocking the spray arm until you’re happy it is spinning freely. 
  • If you can’t find any obstructions but there is some resistance when turning the spray arm, it may not be installed properly. Spray arms screw into place, and if the upper arm isn’t correctly threaded, it could be unable to turn. Try unscrewing the spray arm, putting it back in place, and then checking to see if it spins freely. 
  • Visually inspect the spray arm to see if it’s cracked or damaged in any way. If there’s damage to the arm, you can order a replacement part that fits your dishwasher model and install it in place of the faulty one. 
  • Once you’ve ensured the spray arm is unobstructed, run a test cycle to ensure the top rack is cleaning properly. 

Blocked Spray Arm

The upper spray arm shoots water upwards towards the upper rack, which cleans the dishes. If it’s spinning freely and there are no overloading or water pressure issues, the most likely cause is the holes in the upper spray arm are blocked. This can happen if you wash your dishes with a lot of debris on them, particularly fibrous items like lentils or corn. These can get recirculated through the dishwasher’s interior and trapped inside the spray holes, blocking the tubes. 

It is also possible for mildew growth to block the spray arms. This is particularly likely if you’ve not used your dishwasher for a while, as the lack of running water going through the spray arms can lead to mildew overgrowth.

To fix this:

  • Unscrew the upper spray arm and place it to soak in warm water and detergent. 
  • After soaking for about an hour, use a long, thin brush or a toothpick to clear the holes on the spray arm. 
  • Use a hose to run water through the spray arm, and check to ensure all the holes flow freely. 
  • Replace the spray arm and run a cycle to ensure your top rack is being cleaned properly.
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