A dishwasher that runs a full cycle and leaves grit behind has almost always lost one of three things: hot water, water pressure at the arms, or the ability to grind what it picks up.
Start with the water temperature
Detergent needs heat to work. If the kitchen tap runs cold for twenty seconds before it warms up, the dishwasher is filling with all of that cold water on every fill. Run the tap hot before starting the cycle and see whether the results change. It is the cheapest test in this article and it explains a surprising share of complaints.
Check the spray arms
Take them out. Most lift off or unscrew by hand. Hold each one up to the light and look through the jets. Seeds, labels off jars and fragments of plastic block them, and a blocked jet leaves a shadow of dirty dishes in exactly one part of the rack. Clear them with a cocktail stick and refit.
While they are out, spin the upper arm by hand on the rack. If it catches, something in the rack above is fouling it, which stops it turning under water pressure too.
The filter and the chopper
The cylindrical filter in the base unscrews. It should be rinsed every few weeks and most people never touch it. Underneath sits the chopper assembly, which grinds food fine enough to drain away. When the chopper blade wears, larger debris circulates instead of leaving, and it lands back on the dishes.
How you load it
Two habits ruin results. Nesting bowls so one shields another, and rinsing plates completely before loading. Modern detergent contains enzymes that need something to act on; a spotlessly rinsed load can come out worse than a scraped one.
When it is a repair
If the water is hot, the arms spin freely and the filter is clean, the next candidates are the wash pump and the diverter that sends water between the upper and lower arms. Both are serviceable. On a KitchenAid the sump is designed to be worked on, so this is a repair rather than a reason to replace the machine.
We repair KitchenAid. Call (973) 226-1000 with the model number from the door frame.
