There’s no question that dishwashers can save time and make life easier – except when they stop working. To help you troubleshoot your ailing dishwasher, here is some basic info on how a dishwasher works along with common issues and repairs.
How a Dishwasher Works
A dishwasher draws about 3 gallons of water to flood the bottom of the tub and mix with the dishwasher detergent. The water is then pumped to the rotating spray arms and through them onto the dirty dishes. The dirty water drains out of the appliance, into the drainpipe, while fresh water is pumped into the dishwasher to rinse the dishes. Typically, the process repeats one or more times to ensure clean dishes.
Of course, this is a simplified version of how a dishwasher works. Various parts work together “behind the scenes” to enable proper operation. A timer, for instance, controls the amount of water. A heating element both heats the water to a temperature of 140 to 160 degrees Fahrenheit (a little hotter than the water supplied by most home water heaters) and allows you to dry the dishes when the cycle is complete.
Troubleshooting by Symptom
Be aware that some problems may cause more than one symptom. Carefully read through the symptoms of some of the most common dishwasher issues and find one that fits your situation. If you decide to perform in-depth repairs, always unplug the unit first to prevent shock. As always, consult a repair professional for troubleshooting and repair work beyond your comfort zone.
Dishwasher Fails to Start but Receives Power
When you attempt to start your dishwasher and nothing happens, look to see if the controls light up or you can find other evidence that the appliance is receiving power. If it’s plugged into an electrical outlet, try plugging in an alarm clock, lamp, or other small appliance to verify that the outlet works.
- Check the door. If the door isn’t properly shut and locked, the dishwasher will not start. Make sure nothing’s blocking the door and the lock isn’t sticking.
- Adjust the door latch. To fix a door safety switch or latch problem, sometimes all it takes is a screwdriver. Unplug or turn off the power at the breaker/fuse box. Lightly pry the door latch strike to adjust slightly. Once the latch makes good contact, it should depress the safety switch and allow the dishwasher to resume operation.
- Replace the timer. Situated inside the dishwasher door, the timer controls the washing and drying cycles by controlling the flow of power to each component inside your dishwasher. A malfunctioning timer may cause the dishwasher to stick in a given cycle, make the cycle run too long, or fail to start completely. In most cases, this is a repair best left to a professional.
- Service the selector switch. Located inside the dishwasher door, the selector switch determines the cycle selected. Without it, the cycle will not work. Consult a service technician for further assistance.
- Test the thermal fuse. Newer dishwashers use a thermal fuse mounted to the control board. If the fuse blows, the dishwasher will not function. Contact a service professional for more information.
- Replace a faulty control board. When the control board dies, so does your dishwasher. A fairly expensive part, you may wish to weigh the cost against the age of the unit.
Dishwasher Fails to Start and is Not Getting Power
The problem lies somewhere between your dishwasher and the incoming electrical current. The fix is usually simple.
- Look at the power cord or wiring connection. Pinched or otherwise damaged cords and wiring, such as those chewed on by animals or melted due to a wiring issue, require replacement. Never operate a dishwasher with damaged wiring or cords.
- Check the outlet. If it’s a GFCI outlet, it also has a reset button. Sometimes resetting the outlet – or any other outlets on the same circuit – will solve the problem. (To identify which outlets are on the circuit, turn off the breaker or fuse that controls the dishwasher and see which other outlets are no longer live.)
- Visit your home’s breaker or fuse box. Locate the breaker or fuse that sends power to your dishwasher. If the breaker is tripped (it will show as halfway between on and off) turn it off then on again. If you have an older fuse box, replace the fuse instead. If you find evidence of a wiring problem – scorched, melted wires or other signs of obvious damage – consult an electrician.
Dishwasher Won’t Fill or Drains During Fill
- Check the dishwasher door. If it isn’t closed and sealed, it will prevent the water from entering. Adjust the latch with a screwdriver, as mentioned earlier, to overcome misalignment.
- Look at the water supply. The shut-off valve is likely located underneath the kitchen sink.
- Clean around the float in case it’s clogged. Look for a dome- or cylinder-shaped plastic item mounted to the base, close to the front of the unit. Lift it out and clean around the exposed tube. In some cases, you must remove the access panel below the dishwasher door to disconnect the float from the bottom. Rinse and replace when finished. Make sure the float moves up and down freely – you should hear a click as it moves, indicating it triggered a lever that controls the float switch, which in turn tells the dishwasher when to shut off the water.
- Check the inlet valve and plumbing pipes. Disconnect the power first – either pulling the plug or turning it off at the breaker box – and remove the access panel under the door. The inlet valve will have hoses running into the valve and out to the dishwasher. Look first for leaks. Next, disassemble the valve to find the screen inside. When dirty it will prevent water from entering the dishwasher. Take a look at the wires running from the valve as well. If they are damaged or the terminals are corroded, the valve may need either cleaning or replacement.
- Test other parts. If the previous steps didn’t resolve the problem, the pressure switch, timer, selector, drain valve lever arm or fill tube may be to blame. Consult an appliance repair technician for more involved repairs.
Dishwasher Won’t Stop Filling
When the water won’t stop flowing, immediately disconnect power to prevent a messy overflow. Have a qualified professional perform repairs beyond your ability.
- Test the float switch. Push the float up and down, listening for a click. Connect a volt-ohm meter and test for continuity. A bad float switch is easily replaced.
- Check the water inlet valve. It may be stuck open. It can be replaced fairly simply and inexpensively if needed.
- Look at the timer. If the timer is stuck in the fill cycle, sometimes you can manually advance the cycle by turning the knob. Alternatively, replace the timer.
Dishwasher Won’t Drain
It’s completely normal for a little water to remain in the bottom of your dishwasher. If there’s an excessive amount of water – more than usual – or if you see the water is dirty, then there’s probably a clog somewhere.
- Clean filters and strainers. After removing them, scrub filters and strainers to remove debris buildup.
- Check the drain. Use a flashlight to peer into it and spot obvious obstructions. Employ a long brush or any tool that won’t pierce the drain to clear the drain.
- Look for any blockages. Check along the length of the drain hose for kinks or pinched areas.
- Check the disposal. If you recently installed the dishwasher or a garbage disposal, check the garbage disposal’s knockout plug as well.
Sometimes the clog will be deeper in the dishwasher system. The drive belt may need replacing, or the timer motor, drain valve or pump may be malfunctioning. These repairs require a little more knowledge to perform. If your previous efforts fail to fix the problem and you don’t feel comfortable attempting to dig deeper, contact a qualified service technician for assistance.
A leaking dishwasher isn’t a good thing. Leaks quickly lead to mold, mildew and rot damage if not corrected quickly. Fortunately, many of the causes are easily corrected. For more in-depth troubleshooting and repair, contact a service technician.
- Are you using a detergent designed for a dishwasher? Are you using the recommended amount? Less isn’t always more. If the detergent suds too much, it could cause a leak.
- Do you load the dishes properly? Improperly arranged dishes may cause water to spill through the door vent.
- Is the door gasket in good condition? Leaking around the door edges may signal a door gasket that needs replacement or a door that needs to be adjusted for tightness.
- Check the dishwasher for level. Use a carpenter’s level and run it from front to back as well as side to side. Adjust the front legs, moving them up or down, to level. Some dishwashers may also have leveling feet at the rear.
- Look at the hoses and hose connections. Remove the service panel, underneath the door, and check each hose for leaks.
- Examine the pump seal and the pump itself. Replacing these parts is complicated and best left to a professional.
Dishes Aren’t Clean
If your dishwasher isn’t doing its job, the fix may be something fairly simple. For more complex repairs, consult a professional.
- Are you loading the dishes properly? The dishwasher’s spray arm is responsible for spreading water across the dishes to clean and rinse. If your dishwasher has one spray arm, it’s important to not overload the bottom tray. Keep the spray arms in mind while loading your dishwasher and consult your owner’s manual for your specific appliance.
- Do you use the proper amount and type of detergent? Check that the detergent isn’t clumped inside the dispenser and that it opens properly during the wash cycle. Replace a broken dispenser as necessary.
- Unclog the spray arms or filter. After unplugging the appliance (or turning off the power at the breaker box) remove the spray arm according to the directions in your owner’s manual. Look for calcium buildup and other debris in the holes covering the spray arms. Use a toothpick or other small tool to clean each hole individually. Alternatively, soak in vinegar to dissolve hard water deposits that clog the holes. Rinse and replace.
- Clean the filter. If it’s also clogged, it could prevent clean dishes. Some filters are easier to access than others.
- Check the spray arms for easy movement. If the spray arms don’t move freely, water will not get to all the dishes. Consult a repair technician for further assistance.
Other potential causes for your dishes not coming clean include using the wrong setting, dishes stacked in such a manner that they block the detergent cup and prevent it from releasing, and cold water due to the heater not working. After eliminating all the causes that you can, consider contacting a qualified service technician. More complex repairs involving the water inlet valve, drain valve, timer motor or selector switch may be necessary.
Dishwasher Makes Strange Sounds or Emits Odors
To combat smells inside your dishwasher, periodically flush it with vinegar or sprinkle a stale dishwasher with baking soda. If the smell is like burning or melting rubber – it probably is. Anything that comes in contact with the heating element in the bottom of the dishwasher is subject to damage. Sounds, on the other hand, can be a little more difficult to pinpoint.
- Are the dishes loaded properly? Consult your owner’s manual for correct loading suggestions. Improperly loaded dishwashers are often noisy dishwashers.
- Can you see silverware or other items at the bottom, near the pump or spray arm base?
- Is the dishwasher level? Adjust the leveling feet as needed.
- Humming sounds usually indicate a dishwasher that wants to run, but can’t. The problem may be a jammed pump, a bad motor or motor start relay, or possibly a broken drive belt. Contact a service technician for further assistance.
- Thumping or chattering sounds occurring during the fill cycle usually denote a faulty inlet valve.
If a repair is likely to take a lot of time or expensive parts, make sure the dishwasher is worth it. Nothing lasts forever, after all. Make sure you do your homework before selecting a new dishwasher. Check reviews and shop around for the best price for you.
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