When your dishes aren’t getting clean, there could be a couple of things causing the problem. If the unit is running properly but your dishes are still coming out dirty, you may have a water flow problem and there are a couple of ways that you can solve this issue.
First, take a look at the spray arm. Removing the arm and cleaning out the holes inside could instantly give you better cleaning power. Keep in mind that while some spray arms simply snap off, others have screws holding them on so be sure that you do not break anything when you remove the arm.
The inlet screen could also be clogged. If this is the case, you may need to clean or replace the screen and/or valve. You just have to disconnect and remove the water line and then take out the valve to replace it. Detailed instructions at Familyhandyman – Dishwasher Repair Tips: Dishwasher Not Cleaning Dishes
Dishwashers tend to accumulate dirt buildup over time. In order to keep it running properly and to ensure that your dishes come out clean, you have to actually clean your dishwasher from time to time. You can begin by simply pulling out the lower rack and checking to see that nothing is clogging up the drain.