Safety Precautions
Your KitchenAid dishwasher is hard-wired with a 120-volt power source to the electrical system in your home. Care must be taken when performing repairs to the dishwasher to avoid injury. Before beginning any repairs, disconnect the dishwasher's power source by turning off the breaker in your home's service panel. When performing repairs, wear gloves to protect your hands from sharp objects in the dishwasher.
Upper Spray Arm Function
The upper spray arm relies on an adequate amount of water pressure to properly function. The water is pumped from the bottom of the dishwasher using a sump pump, up the water supply tube on the rear wall of the dishwasher and through the spray arm. The water pressure causes the spray arm to rotate rapidly as water passes through the nozzles, spraying onto the dishes on the top rack.
Examine the Spray Arm
If the spray arm is damaged, it might not rotate. If the spray arm frequently comes in contact with bulky items on the bottom rack below it, the spray arm could crack or break, preventing it from rotating. Further, hard water and detergent deposits may cause the nozzles on the spray arm to become blocked, preventing water from passing through the nozzles. To replace or clean the spray arm, you must first remove it from the bottom of the dish rack. The spray arm is secured using a screw or bolt at the bottom of the arm. When cleaning the spray arm, use a soft bristle bush and pipe cleaners to clear the nozzles.
Food Chopper
If the upper spray arm is not damaged and the nozzles are not clogged, the problem often lies in the food chopper. The food chopper is located below the dishwasher's filter housing and has a blade that pulverizes food particles, preventing the pump from clogging. If the food chopper is damaged, a clog will begin to form that eventually reduces the pressure of the water sent to the upper spray arm. To correct this problem, disassemble the dishwasher's lower filter assembly and remove any food particles by hand. Once the food is removed, inspect the food chopper; if it is damaged, replace it.