Dishwashers seem like a housekeeping marvel until they cease to work properly. Even old dishwashers can be kept at optimal performance with a little maintenance and know-how. Problems like soap not dissolving may be simple and easy to fix.
Hard and Soft Water
If you have hard water, your dishwasher requires more detergent than if you have soft water. However, loading up the dishwasher with more detergent may result in it not dissolving. Experiment with different amounts of powder detergent to see how much is too much and how little still gets the dishes clean.
Switching to a gel or liquid dishwashing detergent is not a solution to resolve powder detergent not dissolving. Gels are undesirable for numerous reasons, including because the chlorine bleach in gel detergents dissolves rubber seals in the dishwasher and gels work poorly in hard water.
Cooler water will not dissolve powder detergents in dish washers as well as hot water. Dishes in the washer should be cleaned with water at least 130 degrees F.
Sometimes the dishwasher drain gets clogged. Run the dish washing cycle with no dishes and a quart of white vinegar to clean and clear the inside of the dishwasher and the drain. Do this once per month to keep the dishwasher working properly, and the powder will dissolve more efficiently.