If you still have caked detergent after running your dishwasher, try these dishwasher troubleshooting tips.
Before doing anything, check out your Use & Care manual to see what kind and how much detergent the manufacturer recommends. Your problem could be as simple as using too much detergent.
If dispenser cup is wet, the detergent can clump. Clean it out and start over.
Is the cycle incomplete?
If the previous cycle did not complete, the detergent can become caked in the dispenser cup if it is left sitting in the dishwasher. This probably isn’t the cause for those with chronic detergent-caking issues. Again, clean the detergent from the cup and start over again.
Is the detergent old?
Older detergent exposed to air will clump and not dissolve well, which will cause the dispenser door to stick to the detergent. Buy new detergent, and this time, keep it in a tightly closed container (i.e. not the box with an open flap) in a cool dry place (i.e. not under your sink right next to the wall where your dishwasher runs hot).
Is the water temperature too low?
For best washing and drying results, water should be 120oF (49o C) as it enters the dishwasher, so check your water heater setting. I also try to remember to run the kitchen sink tap until hot water comes out to help this.
Were items blocking the dispenser that kept it from opening?
Items blocking the detergent dispenser will keep it from opening. Make sure water action can reach the dispenser.
Other good detergent guidelines:
Use automatic dishwashing detergent only.
Add detergents just before starting the cycle.
The amount of detergent to use depends on the hardness of your water and the type of detergent.
Your manufacturer’s suggested amount is based on standard powdered detergent, so follow instructions on the package when using liquid or concentrated powdered detergent.