Ultimate Fix-It-Yourself Manual: Large appliances--Dishwashers

Note: Details of repair and disassembly may vary, depending on appliance model. If your dishwasher differs markedly from this one, see Appliance repair basics.

When you turn on a dishwasher, about 2 gallons of hot water enters the tub, mixes with detergent delivered by the dispenser, and is pumped through the rotating spray assembly onto the dishes. The tub then empties and refills with fresh water that is sprayed to rinse the dishes. Most machines repeat this wash- and-rinse cycle at least once. A heating element maintains the water at 140° to 160° F, the tempera ture needed to dissolve grease. After the tub empties for the last time, the heating element, or an energy-saving combination of an element and a blower, dries the dishes. A timer controls the process.

Most dishwasher problems stem from improper loading, stale detergent, minor block ages, and low water tempera ture or pressure. To test your home’s water temperature, run very hot water into a glass in the kitchen sink, and insert a meat thermometer. If it reads below 140° F, insulate the pipes between the water heater and the dishwasher. If needed, raise the water heater setting, but not if there are children or others in the house who might scald themselves.

Air gap on drain line, required by some codes, keeps dirty water from reentering dishwasher. Clear an air gap regularly to prevent overflows. Cover.

= = = FOR YOUR SAFETY = = =

Shut off power to a dishwasher at the service panel before disassembling or working on it. If a unit leaks or sparks, don’t touch it until you’re sure the power is off. Let the unit cool before touching internal parts, especially the heating element.

Shut off the water supply to a dishwasher before disassembling or making repairs. Keep electrical parts dry; water on them can create shock and tire hazards and cause parts to short-circuit when you turn on power to the unit.

Place sharp utensils like knives so that the points face down. Keep them away from the door seal; one might puncture it and cause the door to leak.

= = =


  • Won’t start
  • Hums but won’t run
  • Doesn’t till
  • Drains during fill
  • Overfills
  • Drains poorly or not at all
  • Leaks around door
  • Leaks underneath
  • Noisy
  • Dirty or spotted dishes
  • Power off at service panel
  • Door not latching or faulty door switch
  • Faulty timer
  • Faulty motor
  • Clogged inlet valve
  • Clogged pump
  • Pump seals binding
  • Faulty motor start relay
  • Faulty motor
  • Float switch faulty or stuck open
  • Faulty or clogged inlet valve
  • Faulty drain valve (some models)
  • Inlet valve not closing
  • Faulty timer
  • Clogged strainer
  • Clogged or kinked drain hose
  • Clogged pump
  • Faulty motor
  • Faulty drain valve (some models)
  • Loose or misaligned door catch
  • Dirty, cracked, or hardened door gasket
  • Loose or cracked hose
  • Loose heating element gaskets
  • Rust-perforated tub
  • Deteriorated pump seals
  • Improperly loaded dishes
  • Foreign object in pump
  • Improperly loaded dishes; stale detergent
  • Water not hot enough
  • Faulty detergent or rinse-agent dispenser
  • High mineral content in water
  • Faulty heating element
  • Faulty selector switch
  • Faulty timer
  • Dirty or faulty pump
  • See General troubleshooting.
  • Adjust latch. Replace switch.
  • Test and replace.
  • Test; repair or replace.
  • Disassemble and clean.
  • Disassemble and clean.
  • Disassemble pump and replace seals. •
  • Test; repair or replace.
  • Test; repair or replace.
  • Check and repair.
  • Test and repair. I Or clean.
  • Test; repair or replace.
  • Disassemble and clean.
  • Test and replace.
  • Clean.
  • Remove and clean; or replace.
  • Disassemble and clean.
  • Test; repair or replace.
  • Test; repair or replace.
  • Adjust.
  • Replace.
  • Replace hose clamp or hose.
  • Tighten or replace.
  • Repair, using epoxy patch kit as directed.
  • Replace.
  • Load correctly.
  • Disassemble pump and remove.
  • Load correctly; use fresh detergent.
  • Check household water temperature.
  • Test; repair or replace.
  • Have water softener installed on house water supply.
  • Test and replace.
  • Test and replace.
  • Test and replace.
  • Disassemble; clean or repair.

[Degree of difficulty: Simple; Average Complex • Volt-ohm meter required: I ]

Gaining access:

To remove dish racks, unsnap and take off caps on front end of tracks. Other racks are held by pins that you pull out, and some racks simply slide out.

To remove spray arm, unscrew spray tower clockwise (it may be tight). Then lift off spray arm; on some models, remove plastic cap or nut to free it first.

To open inner door panel, take out screws on door’s inside rim; lift up panel. On some models, outer panel opens after you re move inside screws or trim.

To access controls, open door panel (left); snap off control- panel cover. On other units, outer panel opens once knobs and inside screws are removed.

To remove lower front panel and toeplate, take out retaining screws. Some models have a single panel that you pull out and lift off hooks.

To disconnect intake line, shut off water at cutoff. Using one wrench to grip elbow under inlet valve, loosen nut on the line with a second wrench.

Door problems:

Examine and adjust the door if it leaks or is hard to close. If adjusting doesn’t stop the leak, suspect a bad door gasket. If a detergent or rinse-agent dispenser malfunctions, open the door panel and check for a stuck lever, broken spring, or other mechanical problem. Some dispensers are triggered by a lever on the timer, others by a solenoid or a bimetal arm. The test below for a solenoid is also valid for a bimetal arm.

A dishwasher door contains one or two switches in the latch assembly that prevent the unit from starting unless the door is latched. If the unit won’t start and the door latches firmly, suspect these switches.

To test dispenser solenoid, take off leads. With VOM on RX100, probe terminals. Look for moderate resistance (about 2,500 ohms). Look for resistance approaching zero on a bimetal arm.

If door won’t latch, reposition door catch (or strike plate). Loosen screw, slide catch mechanism inward or out; retighten firmly. Door should close tightly when latched, compressing gasket.

If door falls open, check the springs. Re-hook a disconnected spring; replace a broken one. To tighten tension, hook spring in a new slot or hole. Keep tension on both springs the same.

If gasket is worn, hardened, or torn, replace it. Unclip, unscrew, or pry off old gasket. If necessary, soak new one in warm water to remove kinks. Attach top, then sides and bottom.

Testing and replacing door switches:

Free the latch assembly by taking out the screws that hold it to the door. Lift the assembly and press down on the latch mechanism to see if it operates the switches properly.

To test each door switch, remove leads and set & VOM on RX1. Probe terminals. Look for zero reading when you press latch mechanism down to closed position, infinity when you release it.

To replace a defective door switch, unclip it and U slide it out of the latch assembly. If necessary, hold down the toggle to get switch out. Switch models vary; some are single rather than double.

To test lever latch switch, open door’s access panel. Remove a lead; set VOM on RX1. With door open, probe terminals; look for reading of infinity. Latch door and repeat; reading should be zero.

Sprayer, strainer, and racks:

To unclog spray arm, gently probe holes with toothpick, awl, opened coat hanger, or other thin wire. Shake and rinse under hard spray to remove particles inside. To remove hard-water mineral deposits, scrub with hot vinegar.

Clean strainer in base of tub if there is one. On some models, also clean the raised guard that pre vents food particles from recirculating onto dishes. Most strainers and guards lift out; some are secured with screws.

To repair chipped rack, remove it from machine, scour away rust with steel wool, then apply epoxy or plastic rack repair compound, or rubber caps—all sold at appliance parts stores. Be sure material is FDA-approved for contact with food.

Replace rollers if broken. Most can be pulled easily from prongs on racks but may need to be unclipped first. If a roller won’t turn, scrub it with a brush and detergent.

Control panel:

Remove the control-panel cover to reach the timer and selector switch. The timer distributes power to other parts of the dishwasher at set intervals. Timers have a small electric motor, which can often be replaced if it tests faulty. Selector switches control special functions such as water preheating, air versus heat drying, or an extra pots-and-pans cycle. Most are simple on-off devices that can be tested as shown below. Solid-state timers and switches can’t be repaired; replace one if it malfunctions.

Test selector switch with VOM on RX1. Take leads off terminals for first push button, and clip probes to terminals. Look for a reading of zero when you depress button, infinity when button is out (vice versa for air-drying but ton). Reconnect leads.

Repeat test for each remaining push button.

To test timer motor, disconnect motor leads from timer. With VOM on RX100, clip probes to leads. Look for a reading indicating moderate resistance. If reading is very high or infinity, replace motor. (To test timer itself)

= = = USE AND CARE = = =

Don’t block the spray arm or spray tower or the flow of water to the detergent dispenser with large dishes, pots, or pans.

Load dishes so they are separated and face the center of the dishwasher. Put glasses between prongs, not over them.

Use dishwasher detergent, never soap, laundry detergent, or dishwashing liquid. Use only fresh detergent; store it in a cool, dry place. Follow manufacturer’s directions for amount. Less is needed if water is soft, more if it’s hard.

Use a rinse agent to speed drying if you have hard water. But don’t use it if your water is soft or artificially softened.

Avoid washing unenameled cast iron or ungalvanized tinware; pewter; fragile, antique, or gold-plated china and glassware; and plastics not labeled dishwasher-safe. The coating on disposable aluminum pans also degrades in a dishwasher.

To ensure the correct water temperature, run hot water at kitchen sink until it feels hot before turning on dishwasher.

To conserve water and energy, run a dishwasher fully loaded at night or during off-peak lower-cost utility hours. In hot weather, run it at night to keep cooling costs down.

Don’t pre-rinse normally soiled dishes. Just scrape off food.

Use the hold-and-rinse cycle only when dishes must be left overnight and odors may result.

Use the lightest washing cycle for dishes that aren’t very dirty. This cycle uses less hot water and energy than others.

Air-dry dishes to save energy when rapid drying is not needed. Don’t warm plates in a dishwasher. Using its drying cycle as a plate-warmer wastes power. Use the oven instead.

= = = =

Water inlet valve:

When activated by current from the timer, the inlet valve’s electromagnetic solenoid moves a metal plunger that opens the valve. When the current goes off, the plunger shifts back, closing the valve.

If a dishwasher doesn’t fill fully, check for a stuck float before testing the inlet valve. To test the inlet valve, shut off both the power and the water sup ply to the machine and open the lower front panel and toeplate. Test the valve solenoid first. If it’s OK, take out the valve and check for a clogged intake filter. When the valve won’t cut off, it’s usually due to a rust or sand particle in the diaphragm bleed hole; disassemble the valve and wash it out.

Test inlet valve solenoid with VOM on RX100. Disconnect a lead and touch probes to both valve terminals; look for a reading showing moderate resistance (500 to 2,000 ohms). If reading is very high or infinity, dismount the valve, detach the sole noid, and replace it.

To clean intake filter, disconnect hose, pipe, and wires from valve, and take out its mounting screws. Pull filter from valve with long-nose pliers or pry out with small screwdriver. Clean under running water with an old toothbrush. If needed, take out screws holding valve together and clean valve. Check for damaged washer. When replacing washer, make sure its beveled side faces out.

Heating element, blower, and thermostats --- A bad heating element or blower can cause poor drying; a faulty thermostat can keep the unit from running at all. When testing the element, check for a ground fault as well: With the VOM on RX100, probe the outer metal surface of the element and each terminal in turn. Both readings should be infinity.

The temperature-sensing thermostat keeps the unit off while the element heats the water during the sanitizing cycle. The limiting thermostat turns off the element if the unit gets too hot; test it as you would a temperature-sensing thermostat (below), but look for opposite results. Turn off power to the unit before working on any of these parts.

Opening the lower front panel and removing the toeplate (see Gaining access) allows you to reach the heating element terminals, the thermostats associated with the element, and the blower, if any. Opening the lower front panel also lets you access and test the float switch and the motor and its start relay. Spray arm; Blower outlet; Start relay (for main motor); Blower; Blower motor

To test element, set VOM on RX1. Take off a lead and probe terminals. Look for reading of 15 to 30 ohms. If significantly higher, element is faulty. If OK, test for ground fault (see text above).

To replace element, disconnect both leads; from below, unscrew retaining nuts from terminals. Then lift element free from above. Install new element, using new gaskets.

To test blower motor, disconnect leads from terminals. Set VOM on RX1, and probe terminals. Look for a reading between 20 and 100 ohms; replace motor if reading is infinity.

To test temperature-sensing thermostat, unclip it and remove leads. With VOM on RX1, clip probes to terminals; look for infinity reading. Hold thermo stat next to a hot light; reading should be zero.

Float switch:

To test float switch, which prevents over flows, first check that float in tub moves freely and is not blocked by caked detergent or debris. Then remove leads from switch terminals. With VOM on RX1, clip probes to switch terminals: look for a reading of zero. Raise float; reading should change to infinity. If switch fails tests, replace it.

Common variant: Drain valve

A dishwasher with a nonreversible motor (see Testing the motor) contains a drain valve that enables the appliance to drain by shutting off water to the spray assembly while at the same time opening the drain hose. The drain valve may be located on the pump or linked to it by a short flexible hose.

Like an inlet valve, a drain valve is actuated by a solenoid. To check the valve, make sure that all exposed moving parts move freely. (Many valves have two springs, which must be intact.) After testing the solenoid, remove the valve and check it for clogs, taking it apart if necessary. You’ll also have to disassemble it if you suspect a faulty seal.

Test drain valve solenoid with VOM on RX1. Disconnect wires and probe both terminals. Look for reading of moderate to low ohms. Replace solenoid if reading is high ohms or infinity.

To remove drain valve, disconnect wires and hoses; unscrew valve from frame. Flush with water to clean. Remove obstructions with long-nose pliers. If necessary, disassemble valve.

Vertical pump and reversible motor assembly:

Pump guard; Chopper blade, Blade mount, Seal, Motor, Motor leads, Support, Shroud

Most pumps are mounted vertically above the motor, which in this configuration is usually reversible. If the motor malfunctions, try turning the lower spray arm, which is mounted on the motor shaft. If it moves freely, the problem is most likely electrical—a stuck relay or centrifugal switch or a faulty field coil (see Testing the motor). If the spray arm doesn’t turn, suspect a clogged pump or a binding pump seal. To repair the pump, turn off power to the dishwasher and remove the entire pump and motor assembly (below). Disassemble and clean the pump; then reassemble it, using replacement seals softened in hot water and coated sparingly with the recommended grease.

To remove pump and motor, disconnect hoses and motor leads. Then pull lever that releases assembly (or unbolt assembly from supports).

Remove spray assembly in tub, and lift out entire pump and motor assembly from above. On some models, motor comes out from below.

Common variant: Horizontal pump assembly:

In some dishwashers, the pump and motor assembly is mounted horizontally. The motor is usually non-reversible and used with a drain valve; the pump has a single impeller instead of the two found in a reversible motor’s pump. To access the assembly, remove the dishwasher’s lower front panel. It the assembly is mounted front-to-back instead of side-to-side, disconnect the water intake line, pull the dishwasher forward, and tilt it up to reach the parts. To repair either pump or motor, remove the entire assembly from the dishwasher. If the motor hums but doesn’t turn, check the pump as described for a vertically mounted assembly.

Testing the motor:

Dishwasher motors are split-phase and usually equipped with a start relay. A motor with four leads is reversible for draining. One with fewer leads is nonreversible and runs only to wash; a drain valve expels the water. To test a motor’s field coil and start relay (below), first identity the common lead (usually the white wire) or check the unit’s wiring diagram. When testing the motor, make sure to do a ground-fault check as well: Set the VOM on RX100, and probe the motor’s metal surface and each lead in turn. Look for a reading of infinity each time.

To test motor field coil, set VOM on RX1. Probe common lead (check wiring diagram, it needed) and each other lead in turn. In all cases, look for low resistance (3 to 15 ohms), indicating significant continuity.

To test start relay, remove leads. Probe common terminal and other two terminals in turn. Look for low ohms on one, infinity on other. Take off relay, turn it upside down, and repeat. Look for the reverse results.

To remove horizontal pump unit, remove spray arm. Disconnect hoses, motor leads, pump clamps, and motor hanger. Pull out.


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