If your dishwasher leaves dishes dirty in one area or makes a constant tapping noise during a cycle, check the spray arm. Utensils can block its movement, while debris in the small openings can interfere with water distribution. Start by checking whether the arm can turn without hitting the load.
How a dishwasher spray arm works
The wash pump pushes pressurized water through small openings in the spray arm. The force of water leaving these directional jets makes the arm rotate and distribute water over the dishes; there is no motor inside the arm itself.
There are two different conditions to check: a blocked arm has an obstacle in its path; a clogged arm has debris obstructing its jets. Whirlpool and KitchenAid also note that extremely hard water can leave mineral deposits on spray arms and other components, reducing cleaning performance.
Signs of a blocked or clogged spray arm
- Constant tapping during a cycle: GE identifies this sound as a reason to check for an item in the arm’s path.
- Poorly washed dishes in one section: GE lists this as another indicator of a blocked arm.
- Detergent or tablets that do not dissolve properly: Bosch links this problem to inadequate water distribution when spray arms are obstructed.
- Visible debris or mineral crust in the openings: these are areas that need cleaning.
On KitchenAid models with a “Top Rack Only” option, the lower spray arm does not engage during that cycle. Check the cycle selection before treating the lack of movement as a malfunction.
How to check and clean the spray arm
- Check rotation before starting a cycle. Turn the middle or lower spray arm by hand. It should complete a full revolution without resistance or contact with the dishes.
- Move obstacles out of the way. If you feel resistance, reposition items touching the arm. Look for wooden spoons, spatulas, cutting boards, large pots and pans, pan handles, and objects hanging below the rack or basket. Check rotation again after rearranging the load.
- Check your model’s manual before removing the arm. The mounting mechanism may use a retaining nut, twist clip, or lift-off design. Follow the removal instructions for your appliance: even models from the same brand can use different mechanisms.
- Clean the jets and bearings. Use warm, soapy water and a soft brush. Use a wooden toothpick to clear debris from individual nozzle holes. When finished, check that no visible debris or mineral crust remains in the openings.
- Reinstall according to the manual. Reverse the removal procedure, making sure the arm is seated and locked in place. Turn it by hand again to confirm that it rotates freely.
How to help prevent future obstructions
Whirlpool’s loading guidance recommends avoiding overloading and positioning items at an angle toward the spray arms without blocking their path.
For their appliances, Whirlpool and KitchenAid recommend using a dishwasher cleaner, such as affresh, monthly to help prevent mineral residue buildup on spray arms and other components. This is a cleaner-use recommendation, not a schedule for removing the spray arms.
When to use the manual or call a technician
If you cannot identify how to release or secure the arm, stop before taking it apart. Follow your model’s owner’s manual; if you need help carrying out that procedure, contact a service technician.
If the jets are clean and the arm turns freely by hand but still does not work during washing, the problem needs further evaluation. GE identifies an inadequate water fill as a separate possible cause from a physical obstruction. Contact a technician to investigate beyond cleaning, rather than proceeding with pump, motor, or electrical disassembly.