Often I get asked “what is the best way to clean a dishwasher?”.
First check the filter, then I recommend Affresh. Affresh is a citric acid based dishwasher cleaner found at most grocery and home improvement stores. Other good ones are: Lemi-Shine, Glisten and Dishwasher Magic. There are others but I have not received significant feedback of their use so I will not mention them at this time. Another natural cleaner/descaler is white distilled vinegar.
But back to Affresh. Simply take the tablet out of the package and throw it into the bottom of the tub. No need to insert into the detergent cup as it may not fit anyway. Select Heavy or Pots/Pans and Sani Rinse or HIgh Temperature options. Also make sure no dishes are in the tub as this cleaner may damage glassware or plate ware. This product also is excellent in solving stale water or odor issues. White distilled vinegar has a place for solving soap build up issues but be careful in over using vinegar as it may damage the plastic parts in the dishwasher. Vinegar is a demineralizer and can cause some damage if used extensively. I recommend filling an ice tea glass (about 12-16 ounces) of vinegar and putting in the upper rack right side up and selecting the heavy setting. As with Affresh may sure no dishes are in the tub. Hope this works!