I agree with Dodgeman’s explanation. My dishwasher just fills up the bottom, then heats the water to a certain temperature and then the pump in the spray arms of the dishwasher cleans the dishes. Check to see if the spray arm filter, in the bottom of the arms, is cleaned out and not clogged up. It usually is easy to remove, but sometimes it can be tricky.

Let us know how it works out.