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My Dishwasher Won’t Drain
We love dishwashers. They are great appliances, they save you time, they save you money and they clean your dishes better than you could ever do by hand but should you do when your dishwasher won’t drain.
Before we answer that I think it’s important to note that there’s a big difference between a good dishwasher and a mediocre one.
So it may be time for you to upgrade to a model that is better suited for your family’s dishwashing needs. Below is a dishwasher buying guide by Consumer Reports.
How Does A Dishwasher Work?
While dishwashers may differ from model to model they all operate on similar principles. A dishwasher has five basic stages that it goes through.
Fill Cycle Stage
In most cases the fill cycle actually begins when draining the water from the appliance. Some of the water is retained in the sump housing to prevent the seals from drying out and cracking when the dishwasher is not in use.
Most dishwashers have a timed fill cycle that will allow no more than two gallons of water to enter during operation. Your home’s water supply line connects to the water inlet valve on the dishwasher.
When you select a wash cycle the controls sends 120 VAC (volts of alternating current) to the inlet valve solenoid opening the valve and allowing the proper amount of water into the tub. Depending on the model the voltage sent by the control will keep the valve open between 90 and 120 seconds.
If the control fails and doesn’t shut off the voltage to the valve a float will actuate a switch that shuts off the water
Keep in mind that the purpose of the float is to prevent your dishwasher from overfilling. The float itself does not monitor or control the amount of water entering the tub.
Having the proper amount of water is vital to your dishwasher’s performance. If the tub is underfilled the dishwasher will not clean properly.
Commonly underfilling is caused by a restricted water inlet valve.
Troubleshoot: To help determine if you have a restricted water inlet valve. Pour 1 -2 quarts of water into the bottom of the tub and run the dishwasher. If the wash performance improves the valve is probably restricted and should be replaced.
Trying to clean out an old valve is not recommended due to the risk of part failure after the repair.
Wash Cycle Stage
Once the proper amount of water enters the tub the washing stage begins. The three factors that affect the wash cycle are water circulation, detergent and water temperature.
To circulate water within the dishwasher the control sends voltage to a circulation motor. The motor drives a pump which uses an impeller to force the water up through the wash arms.
The arms are driven by the water jetting out of the holes. If the arms aren’t rotating or you’re experiencing poor wash performance the cause could be a damaged or worn impeller.
As the food debris is cleaned from the dishware it collects in the sump which filters and retains the larger particles. This filter prevents the food particles from being circulated through the wash arms.
Over time some particles may still reach the wash arms, clogged the holes and reduce wash performance.
Troubleshoot: Remove the wash arms and clean out the holes periodically.
Also, be aware for the wash arms to feel a little loose when not in operation. As the water circulates through the arms a wax motor or solenoid causes the dispenser to open, releasing detergent that mixes with the water.
Since dishwasher detergent doesn’t create suds like other detergents or soaps you should only use detergent designated for dishwasher use. You should also be aware that too much detergent may result as pitting or etching on glassware so follow manufacturer’s recommendations.
Depending on the setting, your dishwasher may use a heating element during the wash cycle. The control will send voltage to the element periodically to maintain a water temperature between 120 and 160 degrees Fahrenheit.
If a problem develops a high-limit thermostat will switch off the voltage to prevent damage to your dishwasher.
Troubleshoot: If you suspect the heating element is not working you can test the element for continuity to determine if a continuous electrical path is present.
Drain Cycle Stage
After the completion of each wash cycle, your dishwasher will drain the dirty water from the tub. The control sends voltage to a drain pump that uses an impeller to force water through the drain hose to a disposal or drain pipe.
This helps ensure proper draining and prevent the water from flowing back into the tub. You must make sure the drain hose has a loop that goes above the drain.
Troubleshoot: If the water does not drain, first check the drain hose for any obstructions. If the hose is clear the drain pump may be defective and require replacement.
Rinse Cycle Stage
Your dishwasher will go through several rinse cycles which are similar to the wash cycles and may also use the heating element. The final rinse cycle introduces rinse aid from the dispenser instead of detergent.
Rinse aid helps to dry the dishware and help prevent streaking caused by hard water. The harder your water, the more rinse aid will be required.
You should consult your owner’s manual to determine the optimal rinse aid setting for your use. Following the rinse cycles will be a final draining cycle.
As we mentioned earlier, some water will remain in the tub to help preserve the seals and prevent cracking.
Dry Cycle Stage
Once your dishware has been washed and rinsed and the water has been drained from your unit the drying process will begin.
Two things are required to dry your dishware efficiently, heat and venting. Some models will use a heating element to heat the elements inside the tub.
Other models will rely on the heat generated by the final rinse cycle. The hot, moist air will either exit through a permanent vent or through a vent in the door which is opened by a wax motor or solenoid.
Without proper venting, the moisture or water vapor would condense back into liquid and collect on your dishware.