This is by far the most common dishwasher complaint; it has several causes. Simply put, a dishwasher sprays and recirculates pressurized hot water onto dirty dishes. It fill and empties numerous times flushing out the loosened dirt.
Poor cleaning is caused by:
1. Not enough water - it must fill the entire bottom of the washer. Poor inlet water flow can be the result of clogged lines or a bad inlet valve.
Occasionally, a fill valve will fill the first or second time, overheat and stop working for the rest of the cycle. A suspect valve can be tested by heating it with a hair dryer.
Heating Water Inlet Valve With Heat Gun
2. Water not hot enough - ideally 140F for good cleaning. Most people have their water heater set around 120F. Most dishwashers boost the temperature with a ring heater in the bottom of the unit. It is always a good idea to run the hot tap to heat up the water pipes prior to running the unit. KitchenAid/Whirlpool dishwashers do a very poor job of cleaning if the heater circuit is broken. A bad heater circuit on many newer models causes the clean light to blink 7 times. See "Blinking Light."
3. Clogged pump inlet or spray arm. Any debris interferring with the recirculation of the water will hamper the cleaning action. Inspect the pump system, spray arm hub, spray arm piping and outlet holes. Any breaks or splits in the spray system must be corrected. Many dishwashers (GE,WP,KA) have a mini-disposer blade at the inlet of the pump. This must be functioning and clear to allow full water flow.
Damaged Whirlpool Chopper
4. Clogged drain system. This will cause dirty water to continuously recirculate. No rinsing action will occur and the dishes will come out cloudy, smeary or dirty.
Results of Poor Draining
5. Bad water may cause buildup thoroughout the entire water system and restrict flow. This will be obvious, but hard to correct. Chemical additives will flush away buildup in some cases. Cleaning out all the passageways is nearly impossible. This is a water expert's problem, not yours.
Calcium Clogs are Extremely Hard to Correct
Poor rinsing of the dishes will result in permanent clouding of glasses. Hand scrubbing will not clean off the haze.
