Short answer
Usually blocked spray arms, a clogged filter, water arriving too cool, or mineral scale coating everything inside. Around here scale is the one people underestimate — a lot of the county runs on well water, and it is hard on dishwashers.
Work through these in order
Pull the bottom rack and take out the filter — most modern dishwashers have one, and most people have never cleaned it. Rinse it under a tap. Then spin each spray arm by hand and check the holes; food debris and scale block them, and a spray arm that cannot spin cleans one small area very well and nothing else.
Then check the water temperature. A dishwasher needs genuinely hot water arriving at it. Running the kitchen tap hot before starting a cycle makes a measurable difference, especially if the machine is a long way from the water heater.
The well-water problem
Out in Scott, Cedar, Mercer and Henry counties a great many homes are on wells, and the mineral content leaves scale on the heating element, the spray arms and the inner surfaces. It looks like a cleaning failure and behaves like one.
When we diagnose a dishwasher outside the towns we check for scale as a matter of course rather than going straight to the pump. Descaling and a change of detergent regime solves a surprising share of these.
When it is genuinely a fault
A failed circulation pump, a broken wash impeller or a water inlet valve that is not filling properly all produce the same symptom. If the filter is clean, the arms spin freely and the water is hot, it is time for us to look at it.
Still not sure how this applies to your machine? Call and ask — we would rather answer a question over the phone than have you guess. We cover Rock Island, the Quad Cities and every community within 50 miles.
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