If your dishwasher doesn't work at all, check these:

Power from the house
Door switch
Wiring
Timer or selector switch

Is there power getting to the dishwasher? This can be difficult to test, because dishwashers are usually wired directly to an electrical circuit, rather than plugged into the wall. But at least check for a blown fuse or a tripped circuit breaker.

The door switch is important because, if it's defective, the dishwasher won't work at all. To reach it, you need to remove the control panel cover, or sometimes the interior liner of the door. If it's defective, you need to completely replace it.

Often the main wiring connection from the house, at the dishwasher, burns and breaks the connection. If that's the problem, the wires must be repaired/replaced as necessary. If that's not the problem, check the wiring to the door switch, the wiring between the door and the lower part of the dishwasher, and the wiring to the timer. Repair any broken, burned, brittle, or defective wiring, using the proper appliance-grade wire and connectors.

Although it's uncommon, the timer or the selector switch may be defective. If so, you need to replace the defective part, because neither of these can be repaired.

If your dishwasher is cleaning poorly, check these:

Water-inlet valve
Internal filters
Drain valve
Spray arms
Water temperature
Detergent cup

Most cleaning problems are caused by the dishwasher not getting enough wash water, so the water-inlet valve is often to blame. This valve is usually at the bottom left or right of the dishwasher, behind the lower access panel. It's the device with the main water line from the house, a rubber tube to the dishwasher, and two wires attached to it.

When a water-inlet valve is defective, you may hear the sound that's usually referred to as "water hammer." If the water-inlet valve is defective, you need to completely replace it.

Every dishwasher has some type of filter to keep large food particles and foreign objects away from the pump assembly:

• Most modern dishwashers have self-cleaning filters that don't need any routine cleaning.
• Some have filters in the bottom of the dishwasher that you need to periodically clean. You don't need any tools to remove the filter, and cleaning it is easy. Consult your owner's manual to determine which type you have and its maintenance requirements.

If your filter is clogged, it may be causing the cleaning problem.

Some dishwashers have a valve (or gate) that should open only during draining. If debris lodges in the valve, it can't close properly, so water drains out during the wash cycle. Most dishwashers drain into the garbage disposer. If yours does that, listen for water flowing into the disposer during the wash cycle. If you can hear it then, the drain valve may be clogged.

There's a spray arm at the bottom of your dishwasher--it may have a tall spray tube mounted to the center of it. There may also be a spray arm located directly beneath the upper rack of dishes and/or above the upper rack.

If debris is blocking the holes in the spray arms where the water comes out, it could cause cleaning problems. Regularly inspect each of the spray arms and clean out the holes as necessary.

To get the best cleaning results, the water entering your dishwasher needs to be hot enough. Try running the hot water in your kitchen sink for about 30 seconds before starting the dishwasher, to pre-heat it. Also, if your dishwasher lets you select a higher wash or rinse temperature, try that to see if it helps.

To check the temperature of the hot water that comes from your kitchen faucet use a waterproof thermometer. If the water isn't 120 degrees Fahrenheit, your dishwasher may have trouble getting your dishes clean. You could increase the temperature of the hot water to the whole house--and therefore the dishwasher--by adjusting the hot water heater thermostat.

Warning! To lessen the risk of scalding, don't set the hot water heater temperature higher than 120 degrees Fahrenheit.

Dishwashers don't perform their best if detergent is introduced only at the beginning of a cycle, so add detergent to both parts of the cup.

If the detergent cup isn't opening, see the "The detergent cup doesn't open" section, below.

If there's no water entering your dishwasher, check these:

Water-inlet valve
Float switch

The water-inlet valve lets water enter the machine. If this valve is defective, you need to completely replace it. It's usually located behind the lower access panel on the left or right side. It's the device with the main water line (usually copper) from the house, a rubber tube to the dishwasher, and two wires attached to it.

The float switch is a small electrical switch that's located right below the dishwasher "floor." Above the switch, on the inside of the dishwasher, is a plastic cylinder that floats up as water fills the dishwasher. If this switch is defective, or if the plastic float gets caught or trapped in the raised position, the water can't enter the dishwasher. If the float switch is defective, you need to replace it.

If the water doesn't drain from your dishwasher, check these:

Drain line/air gap
Pump
Drain valve and/or solenoid
Belt
Motor
Timer

A clog in the drain line or air gap (if there is one) is the usual reason that a dishwasher won't drain. Often the problem is at the point where the drain line attaches to the garbage disposer or household drain line. If you remove this line, you can clear any debris from the hose or hose connection. Be sure to reattach the hose before starting the dishwasher again.

Your dishwasher pump ejects the water. The pump is usually mounted directly to the motor, then attached to the bottom of the dishwasher. You can reach the pump from inside the dishwasher, but first you need to remove the lower rack, the spray arm, and the spray arm support.

Look for an impeller--a round plastic fan blade-type of device that spins around. This is the wash impeller, which forces the water through the spray arm. Beneath the wash impeller is the drain impeller, which is similar in size and shape to the wash impeller. The drain impeller pushes the water toward the drain port. These components make up the pump. If any of the pump components are defective, you need to replace them.

Many dishwashers use a drain valve with an electric solenoid. When electricity flows to the solenoid, the valve opens and diverts the water to the drain. Sometimes the solenoid, or the diverting lever, sticks and prevents the dishwasher from draining or filling properly. Try to free up the solenoid to lubricate the lever. Otherwise, you may have to replace the solenoid or pump assembly. With these systems, the motor always rotates in one direction. When it's energized, the drain valve diverts the water.

Other dishwashers simply reverse the direction of the motor to drain the dishwasher. These units don't have a drain valve. Instead, there's a drain hose connected directly to the pump housing.

One brand of dishwasher uses a belt to drive the pump. If this belt is broken or has fallen off, replace it.

If the motor isn't turning or working, the unit won't drain. First check to be sure you have power to the dishwasher. If not, see the section "It doesn't work at all." If the motor hums but doesn't turn, it may need to be replaced.

Some dishwashers are susceptible to getting stuck if you don't run them regularly. If you haven't run the dishwasher for more than a week, you may need to manually spin the motor to free it up. If the motor is defective, you need to replace it. Dishwasher motors can't be serviced.

Part of what the timer does is control the motor and drain valve. If the timer doesn't work properly, the water may not drain and you need to replace the timer. This problem is uncommon.

If your dishwasher seems noisy, check these:

Water-inlet valve
Motor
Heater fan
Pump

An aging water-inlet valve can sometimes fail slowly, rather than all at once. It can shudder on and off rapidly, causing the incoming water lines to shake, rumble, and rattle--sometimes violently. If yours is doing this, replace the inlet valve.

If it's the motor that's noisy, either of these may be the "culprit:"

• As motor bearings wear out, they can become quite loud when the motor runs. They wear out quickly if they frequently get wet, because the water washes away the motor bearing grease. Bearings can get wet if the spin seal is defective. Then there will also be water leaking onto the floor beneath the dishwasher. Replace the seal if it leaks (read about the main tub seal in the "It leaks" section, later).
  
• If, from beneath the dishwasher, you can see a round, plastic disc that's mounted to the top of the motor (a "slinger"), it may have broken free of the motor shaft. If so, it could be rattling around the shaft while the motor is running. If that's the problem, you need to replace the motor.

If the heater fan bearings are rusted or worn, they may squeal, or scrape loudly during the drying cycle. If this is the problem, replace the fan motor. Alternatively, the fan blade may be loose. If so, you need to replace it.

Small fruit pits, toothpicks, and fragments of glass sometimes get stuck in the pump. When this happens, open the pump and remove the debris. The pump is usually mounted directly to the motor, then attached to the bottom of the dishwasher.

To get to the pump, you usually need to remove the lower rack, the spray arms, and the spray arm support from the inside of your dishwasher. A dishwasher pump isn't obvious. Look for an impeller--a round, plastic fan blade-type device that spins around and pushes the water toward the drain. When you can see the drain impeller, you should be able to see the clogging debris.

If your dishwasher leaks, check these:

Main tub seal
Door gasket or seal
Water-inlet valve
Hoses

Note… If the main motor of your dishwasher is mounted vertically, beneath the center bottom of the dishwasher, the following instructions probably apply to you. But if your motor is mounted horizontally, the pump isn't serviceable--you need to replace the entire pump and motor assembly.

The main tub seal is beneath the drain impeller. It prevents the water in the dishwasher from leaking out near the shaft of the motor. To get to the seal, which is inside the dishwasher, remove the:

• Lower rack
• Spray arm
• Spray arm support
• Wash/drain impellers

Then pry the seal out of its housing and replace it.

Over time, door gaskets and seals harden and lose their ability to seal properly. You can't repair the seals. You need to replace them if they've begun to leak.

The water-inlet valve, itself, seldom leaks. But, the water-supply line from the house and the rubber tube leading from the valve to the inside of the dishwasher may leak. Tighten or repair/replace these as necessary.

The water-inlet valve could mechanically stick open. When that happens, the water continues to flow into the dishwasher, which then floods your kitchen. Turn off the water supply to the dishwasher, and replace the valve.

Behind the lower access panel on your dishwasher are several rubber or plastic hoses. If the leak appears at a connection, try a new clamp. If that doesn't work, replace the hose.

If the dry cycle has a problem, check these:

Heating element
Drying fan
Thermostat

Your dishwasher has an electrical heating element that helps to dry the dishes. If the element is burned out, the dishes won't dry properly, and you need to replace the element.

Many high-priced dishwashers have a small fan that blows air or heated air into the dishwasher to speed up the drying process. If the fan is defective, you need to replace it.

Some dishwashers have a thermostat that monitors the drying temperature. If the thermostat is defective, the heating element may not cycle on or off properly. If that's the problem, you need to replace the thermostat.

When your dishwasher door has a problem, check these:

Latch
Springs
Hinges
Door seal

The latch on many dishwashers is adjustable. If your door is easy to close but difficult to latch, adjust the latch to let the door close more easily. If you can't see any way to adjust the latch, yours may be fixed in a certain position. Check for other reasons for the latching problem.

If the latch has worn out in a way that makes it impossible for you to close the door properly, you probably need to replace the latch.

Your dishwasher has two springs that counterbalance the weight of the door. If either or both of these are broken, the door feels quite heavy and you need to replace both springs.

The hinges are important to the door closing properly. If they're bent or deformed, you probably need to replace them. Once bent, only rarely can they be straightened well enough.

If your dishwasher is new--or if you have just replaced a door seal--the door may be difficult to latch for a week or two. If the tightness persists, though, try adjusting the latch, if it's adjustable. If it's not adjustable, there's probably nothing you can do immediately. But try running the dishwasher on the highest heat cycle to help the seal conform to the door. Otherwise, the seal should compress over time.

If the cycle doesn't complete, check these:

Water-heating cycle
Timer

Many dishwashers heat the wash and/or rinse water to a higher temperature, as the cycle calls for it. In these cycles, the dishwasher pauses after it has filled with water, waiting for the water to reach the pre-set temperature. What happens next, depends, as follows:

• On some units, the pause is timed and the unit continues after the allotted time.
• On others, the cycle can't continue until the water reaches the higher temperature. If you have this type of dishwasher and the water isn't being heated (say, because of a problem with the heating element or thermostat), after the unit stops at the heating cycle, it never continues. When you repair the heating-system problem, the "cycle problem" is fixed too.

Timers don't often fail. But if every other part of the dishwasher seems to be working properly and the timer knob seems to be stuck in one place--doing one function continuously--the timer may be at fault. Dishwasher timers can't be repaired. If yours is defective, replace it.

If your dishwasher has a digital readout and you see an error code, it may indicate a problem with the unit. If this happens, look up the error code in your owner's manual to find out what the problem is.

When the detergent cup doesn't open, check these:

Timer
Bi-metal switch or wax motor
Detergent cup, itself

On many dishwashers, a plastic actuator arm mechanically links the timer to the detergent cup. When the timer reaches the proper time in the cycle, the timer activates a lever that opens the detergent cup. If the linkage is broken or defective, the cup stays closed after you've closed it. Check the link and repair or replace it, as necessary.

A bi-metal switch is a simple electrical device that deforms when electricity is applied to it. The degree of this deformation can be engineered to concise standards.

The timer energizes the bi-metal switch inside your dishwasher door--directly behind the detergent cup--when the detergent cup should open. When energized, the bi-metal switch deforms away from the detergent cup latch, which opens the detergent cup. If the bi-metal switch is defective, it may not deform enough to open the cup. If that happens, you need to replace it.

On some dishwashers, the bimetal switch is wired through the heating element or motor circuit. If the element is broken (or open), or if the motor is drawing low current because of a low-fill situation, the bi-metal switch doesn't open properly.

Newer dishwasher models use a wax motor instead of a bi-metal switch. It's a sealed unit with wax that heats up and pushes a piston through to open the door. The wax motor, controlled by the timer, mechanically opens the door.

The detergent cup itself can become clogged with old dried detergent that prevents it from opening. Sometimes just cleaning the cup takes care of the problem. If not, you probably need to replace the entire cup assembly

If your dishwasher's cycle times are too long, check these:

Water pre-heating
Cycle not completing

Your dishwasher may pre-heat the water. If so, and if the water entering the dishwasher is cool, the heater may take up to half an hour to heat the water.

To avoid the wait, increase the incoming water temperature before turning on the dishwasher. Do that by running the kitchen sink faucet until the water runs hot. Or increase the temperature of the hot water to the entire house at the hot water heater.

Warning! To lessen the risk of scalding, don't set the hot water heater temperature higher than 120 degrees Fahrenheit.

See "The cycle doesn't complete" section.