Most dishwashers dispense the detergent via gravity and the sprayer
arms spraying against the soap dispenser once the little door flips
open during the wash cycle. Since it sounds like the soap door is
opening I would look at the sprayer arms and make sure they are free of
food particles or other debris that might be keeping them from rotating
and spraying properly. Here are some instructions for performing this
Remove the lower dishrack from the unit.
Reach into your dishwasher and spin the lower spray arm. Take note of
whether or not the arm moves freely or if its movement is restricted.
It should not be restricted in its path of motion. Now gently pull up
on an end of the spray arm. The spray arm should be free to wobble up
and down. Unscrew the arm retaining knob (some of these are left hand
threads) and take the arm out for inspection and carefully examine the
spray arm seams. If they have split or are damaged, the dishes may not
receive the amount of water pressure required to fully clean the dishes
or to rotate the arm properly. What’s more, if water is in fact
spraying out of the spray arm from its seams, it is possible that it
can cause your dishwasher to leak. Make sure there is no debris in any
of the holes.
If your dishwasher has a spray tower,
pull up on it as far as it will go and then let it fall back down.
Again, this movement should not be restricted. It should be a fluid and
smooth motion. Also, unscrew the spray tower and examine it for any
debris or foreign objects. Remove any that you find.
Gain access to the upper spray arm by
removing the upper dishrack. Perform the same tests for the upper spray
arm as you just did for the lower spray arm. Keep in mind that the
upper spray arm may not wobble as much as the lower spray arm.
On a final note, some dishwasher models
have a water tube that meets up with the upper spray arm once the upper
dishrack is pushed back. It is a good idea to check to make sure this
tube is aligning properly with the upper spray arm and that this has
not split or is damaged in any other way.