I have never had mold build up in any dishwasher I have owned, but I have had a film/scale develop that Tang has taken care of easily. I did find the below information from a web site once, when I was looking for information about cleaning the interior of my dishwasher.
Step 1: Check the temperature preset before cleaning your dishwater. This is the temperature of the water used for washing. Some dishwashers require water to be 120 degrees or higher, while others require 140 degrees or higher. Check your dishwashers make & model mentioned in the users manual. Learn if your dishwasher has a pre-heating mechanism for water when it is too cold. Use a thermometer to measure the temperature just before the washing cycle begins.
Step 2: Identify and locate the type of cleaning required in your dishwasher. Check the manufacturers booklet that came with your dishwasher, or check the manufacturers web site. Scale, rust, mold, discoloration and food stains are some of the most common concerns that require regular cleaning. Follow the steps below to clean each of these...
Step 3: Add one tbsp of bleach after emptying the contents of dishwasher. Run a full cycle. This will clean any mold built up in the dishwasher and leave the dishwasher sparkling and glowing.
Step 4: Try cleaning discoloration and scale off your dishwasher by adding one half container of Orange Tang Drink Mix. The citric acid present in the mixture helps to loosen up the hard water deposits as it removes and cleans the scale from your dishwasher. Run a regular cycle.
Step 5: Place a coffee cup filled with vinegar in the dishwashing rack and run a full cycle of dishwashing. This will clean your entire dishwasher. This is one of the easiest techniques and works well as preventive care. If vinegar is unavailable you can also use baking soda.