How to fix a dishwasher? | Dishwasher Problems and Solutions
Unlike some other under counter kitchen cleaning appliances, such as the garbage disposer and trash compactor, which work on the principle of the chain reaction, the dishwasher is controlled by a central timer that puts it through its paces. This timer commands the dishwasher to perform its four basic tasks: filling with water, spraying dishes to wash or rinse them, draining water out and drying the dishes with heat and circulating air.
When a dishwasher malfunctions, the trouble is often signaled by a failure to perform one of these tasks. Water does not enter the machine, dishes emerge from the appliance dirty, water remains in the bottom of the tub after the drain cycle is over, or the dishes do not dry. But pinpointing the actual source of the trouble can be difficult.
A dishwasher that drains poorly is in many cases suffering from a clogged air gap, which is easily cleared. The air gap is a plumbing part required in many, though not all, local codes that prevents water in the sink drain from backing up into the dishwasher.
If the air gap is not responsible for the poor drainage, look next at the dishwasher's pumping mechanism. Occasionally the pump impellers become clogged or broken, so water is not pumped through the spray arms during the wash or rinse cycle, or out during the drain cycle. The pump can be disassembled so that impellers can be replaced.
If the pump motor itself wears out, it too can be replaced. It is usually removed as a unit: Release the clips that lock the motor in place under the tub, and lift it up through the tub. On a few dishwasher models, water is drained not by a reversing pump motor but by a drain valve; this valve may clog or stop working because of an electrical problem. To clear an obstruction, flush the valve with water; for an electrical problem, replace the solenoid that operates the valve. If necessary, the entire valve can be replaced.
Dishwasher doesn't clean dishes well !!!
When a dishwasher does not clean dishes well, it usually is because the water entering the dishwasher is not hot enough. Check the temperature of the hot water at the sink by running water over a meat or candy thermometer for two minutes; if the thermometer reads less than 140° F., turn the water heater's controls to a higher temperature setting. If this measure fails (which can happen if the hot water pipes run through unheated parts of the house, such as a crawl space or a basement) wrap the pipes with pipe insulation, available at home improvement centers.
If water temperature is not the problem, it may be that your detergent is too old. If it dissolves too slowly and leaves a gritty residue when placed in a glass of hot water, replace it. Sometimes, too, using a different brand of detergent will improve the dishwasher's performance, especially in hard water areas.
If the movement of the spray arms is blocked by debris or improperly arranged dishes, cleaning performance will be poor. Test the action of the arms by closing the dishwasher and running it briefly on the wash cycle, then open the door; if it looks as though the arms have not moved, clean them. If this remedy does not produce clean dishes, disassemble the pump and inspect the upper impeller for teeth that are broken or clogged. Then examine the water inlet valve, which may be failing to allow enough water to enter the tub; or a float may be sticking, shutting off the water inlet valve.
Finally, poor cleaning may be the result of low water pressure in the house waterlines. Since the timer lets hot water into the dishwasher for a preset period of time, less water enters the machine when the pressure is low. To test the water pressure, turn on the dishwasher and let it fill. Then siphon out the water into containers; there should be 2/1 U.S. gallons (2 imperial gallons). If water pressure is the problem, run the dishwasher only when no water is being used elsewhere in the house.
Dishwasher won't start but has power
When a dishwasher does not run at all, the trouble may be simply a defective door latch or switch. If the dishes do not dry well, check the heating element or, in a model that has one, the blower.
Dishwashers can leak either through a slipped or worn gasket or through poor hose connections and pump seals. Reseat a slipped door gasket with a screwdriver or a pair of pliers. Replace a worn gasket by following the manufacturer's instructions for inserting a new one. To trace hose leaks, observe the character of the water. Clear water indicates a leak during the fill cycle, which means a faulty hose connection at the water inlet valve. Sudsy water is a sign of leaks during the wash, rinse or drain cycles, from hose connections at a pump or, in a model that has one, the drain valve. If a hose is simply loose, tighten or replace its clamp; if it is cracked or brittle, replace the entire hose assembly.
Dishwasher Repair
Before attempting any repair on a dishwasher, turn off the power to the machine at the house service panel. To work on parts located on the underside of the tub the water inlet valve, drain valve, pump motor, float switch or pressure switch, heating element or blower unscrew the lower access panel. Before removing a water-inlet valve, shut off the hot water valve under the sink or the hot water supply valve at the water heater. To replace a faulty detergent dispenser, unscrew and remove the panel on the front of the door; to service the timer, remove the control panel over the door.
Although all dishwashers have wash, rinse and dry cycles, some models have special features such as a selector switch, which alters the operation of the timer to provide a choice of short or long wash cycles. Also, the mechanical parts may differ. On the model below, a spray tower guides water, pumped at very high pressure, up into the upper spray arm; on other models there is a pipe that performs this function. On some machines, a drain valve and a one way pump replace the two way pump shown here. To dry dishes faster, some dishwashers have a blower unit in addition to the heating element. And the job that is usually handled by a float switch is, in a few models, performed instead by a pressure switch, which is mounted either inside or under the tub.
Unclog the holes in the upper spray arm without removing the arm from its holder. If there is a spray arm at the top of the dishwasher tub, clean it while it is in place also.
To clean the lower impeller, unfasten the screws holding the pump guard and remove the guard. Then pull off the pump plate, but do not remove the lower impeller unless it has broken blades and needs to be replaced. To replace the lower impeller, pry if off with a screwdriver or pull it straight off the shaft with a pair of locking pliers. When you install a new impeller, replace the existing seals as well.
Reassemble the pump by reversing this procedure, reattaching the screws first by hand and then driving them in with a screwdriver until the parts fit snugly together.
If the filter is clean, check the condition of the diaphragm in the solenoid assembly that controls the operation of the valve. Unscrew the solenoid mounting, disassemble the spring activated plunger and its guide, and replace the diaphragm. Then reassemble the valve and reattach it to the dishwasher water connections.
If the seal is deteriorated, replace the valve.If the drain valve resembles a water inlet valve, repair it as you would the water inlet valve.
If the overflow is controlled instead by a water pressure switch mounted inside the tub (bottom inset), test the terminals for continuity as above. If there is no continuity, replace the switch. To replace a water pressure switch, unfasten the switch wires, unscrew the nuts under the tub that hold the switch, and lift it out of the tub. Install a new switch by reversing these steps.
In order to install a new heating element, position a pair of new gaskets over the holes in the tub and insert the two ends of the element through the holes. Then fit two new gaskets over the protruding element ends on the underside of the tub, and screw the nuts back into place. Reattach the leads. Turn on the power to the dishwasher, run the machine and look for leaks around the mounting. If you see that water is leaking out, tighten the nuts.
To check the heater's mechanical parts, unscrew the blower unit and pull it down and out of the dishwasher. Check the fan for obstructions by rotating the blades with your hand. If the motor has been noisy and there are oil holes, oil it with a light oil such as sewing machine oil.
With the door open, test the switch terminals a second time for continuity. If there is continuity this time, the switch must be replaced.
If the wires and terminals are sound, check the switch terminals for continuity. If the switch is defective at any setting, replace it.
When a portable does not roll easily, spin the casters to see whether they turn. Clean a dirty bearing with a damp cloth and lubricate it with light oil; replace the entire caster if the tire is split, if the caster does not swivel, the shank may just need tightening; if the shank is bent, replace the entire caster.
When the electric cord does not retract, unscrew the back service panel or lay the dishwasher on its side, and check the rewind reel. If the spring or cable holding the reel is disconnected or broken, reconnect or replace it. If the cord winds so loosely that it comes off the reel, adjust the cord guide bracket, located where the cord enters the reel, until the cord rewinds properly.
The parts of a leaky faucet coupler assembly that can be replaced separately are the washers and adapters that connect the head to the coupler. If the coupler leaks anywhere along its two hose lines, the water inlet hose or the coupler must be replaced. To replace the coupler, remove the top from the machine and tip it over on its side.
Disconnect the drain hose from the pump and the fill hose from the water inlet valve. Set the machine upright and remove the hoses. Then feed the hoses of a new coupler into the machine, threading them through the hose guides. Once again turn the dishwasher on its side, and reconnect the hoses.
When a dishwasher malfunctions, the trouble is often signaled by a failure to perform one of these tasks. Water does not enter the machine, dishes emerge from the appliance dirty, water remains in the bottom of the tub after the drain cycle is over, or the dishes do not dry. But pinpointing the actual source of the trouble can be difficult.
Dishwasher Problems and Solutions
Most commonly the problem is clogging. If there is no clog, look for a mechanical or an electrical failure. Only then should you check the timer; although the timer makes everything happen, it rarely is responsible for breakdowns. Suspect the timer only when the dishwasher does not advance.A dishwasher that drains poorly is in many cases suffering from a clogged air gap, which is easily cleared. The air gap is a plumbing part required in many, though not all, local codes that prevents water in the sink drain from backing up into the dishwasher.
If the air gap is not responsible for the poor drainage, look next at the dishwasher's pumping mechanism. Occasionally the pump impellers become clogged or broken, so water is not pumped through the spray arms during the wash or rinse cycle, or out during the drain cycle. The pump can be disassembled so that impellers can be replaced.
If the pump motor itself wears out, it too can be replaced. It is usually removed as a unit: Release the clips that lock the motor in place under the tub, and lift it up through the tub. On a few dishwasher models, water is drained not by a reversing pump motor but by a drain valve; this valve may clog or stop working because of an electrical problem. To clear an obstruction, flush the valve with water; for an electrical problem, replace the solenoid that operates the valve. If necessary, the entire valve can be replaced.
Dishwasher doesn't clean dishes well !!!
When a dishwasher does not clean dishes well, it usually is because the water entering the dishwasher is not hot enough. Check the temperature of the hot water at the sink by running water over a meat or candy thermometer for two minutes; if the thermometer reads less than 140° F., turn the water heater's controls to a higher temperature setting. If this measure fails (which can happen if the hot water pipes run through unheated parts of the house, such as a crawl space or a basement) wrap the pipes with pipe insulation, available at home improvement centers.
If water temperature is not the problem, it may be that your detergent is too old. If it dissolves too slowly and leaves a gritty residue when placed in a glass of hot water, replace it. Sometimes, too, using a different brand of detergent will improve the dishwasher's performance, especially in hard water areas.
If the movement of the spray arms is blocked by debris or improperly arranged dishes, cleaning performance will be poor. Test the action of the arms by closing the dishwasher and running it briefly on the wash cycle, then open the door; if it looks as though the arms have not moved, clean them. If this remedy does not produce clean dishes, disassemble the pump and inspect the upper impeller for teeth that are broken or clogged. Then examine the water inlet valve, which may be failing to allow enough water to enter the tub; or a float may be sticking, shutting off the water inlet valve.
Finally, poor cleaning may be the result of low water pressure in the house waterlines. Since the timer lets hot water into the dishwasher for a preset period of time, less water enters the machine when the pressure is low. To test the water pressure, turn on the dishwasher and let it fill. Then siphon out the water into containers; there should be 2/1 U.S. gallons (2 imperial gallons). If water pressure is the problem, run the dishwasher only when no water is being used elsewhere in the house.
Dishwasher won't start but has power
When a dishwasher does not run at all, the trouble may be simply a defective door latch or switch. If the dishes do not dry well, check the heating element or, in a model that has one, the blower.
Dishwashers can leak either through a slipped or worn gasket or through poor hose connections and pump seals. Reseat a slipped door gasket with a screwdriver or a pair of pliers. Replace a worn gasket by following the manufacturer's instructions for inserting a new one. To trace hose leaks, observe the character of the water. Clear water indicates a leak during the fill cycle, which means a faulty hose connection at the water inlet valve. Sudsy water is a sign of leaks during the wash, rinse or drain cycles, from hose connections at a pump or, in a model that has one, the drain valve. If a hose is simply loose, tighten or replace its clamp; if it is cracked or brittle, replace the entire hose assembly.
Dishwasher Repair
Before attempting any repair on a dishwasher, turn off the power to the machine at the house service panel. To work on parts located on the underside of the tub the water inlet valve, drain valve, pump motor, float switch or pressure switch, heating element or blower unscrew the lower access panel. Before removing a water-inlet valve, shut off the hot water valve under the sink or the hot water supply valve at the water heater. To replace a faulty detergent dispenser, unscrew and remove the panel on the front of the door; to service the timer, remove the control panel over the door.
Anatomy of a dishwasher
Almost every part of a dishwasher is operated by the timer, which opens the water inlet valve to fill the tub, turns on the pump and opens the detergent dispenser to wash the dishes, reverses the pump to drain the tub, and turns on the heating element to dry the dishes. Only the float switch, an emergency device that turns off the water inlet valve to prevent the tub from overfilling, works independently of the timer.Although all dishwashers have wash, rinse and dry cycles, some models have special features such as a selector switch, which alters the operation of the timer to provide a choice of short or long wash cycles. Also, the mechanical parts may differ. On the model below, a spray tower guides water, pumped at very high pressure, up into the upper spray arm; on other models there is a pipe that performs this function. On some machines, a drain valve and a one way pump replace the two way pump shown here. To dry dishes faster, some dishwashers have a blower unit in addition to the heating element. And the job that is usually handled by a float switch is, in a few models, performed instead by a pressure switch, which is mounted either inside or under the tub.
Five Places to Look for a Dishwasher Obstruction
Opening a clogged air gap
Pull the chrome cover off the air gap, located next to the faucet at the sink, and unscrew the plastic cap under the cover. With tweezers, remove any debris such as glass, bones or toothpicks from the small tube in the center of the air gap. Run the cover and cap under water to clean them. Screw the cap back and put the cover on again.
Cleaning the spray arms and filter screen.
Slide out the lower dish rack, unscrew the plastic hubcap that holds the lower spray arm in place and lift off the spray arm. Unsnap the coarse strainer and lift out the filter screen. Clean the slotted holes on both sides of the spray arm with a stiff wire, bent at a right angle at the tip. Then rinse the spray arm, the strainer and the screen under running water, scrubbing the screen and strainer with a stiff brush, if necessary, to clear their perforations.Unclog the holes in the upper spray arm without removing the arm from its holder. If there is a spray arm at the top of the dishwasher tub, clean it while it is in place also.
Servicing the pump
On this typical pump, take off the lower spray arm (opposite, bottom), and remove the pump cover by turning and lifting it, exposing the upper impeller. To remove the upper impeller, bend the bolt locking tab up to clear the bolt; unscrew the bolt, freeing the impeller. Check the impeller for debris and for worn or broken blades; clean or replace the impeller as necessary. Next, lift out the spacer plate and the food disposer blade under the impeller; clean the blade.
Reassemble the pump by reversing this procedure, reattaching the screws first by hand and then driving them in with a screwdriver until the parts fit snugly together.
Repairing the water inlet valve.
With the power to the dishwasher off, test the solenoid terminals of the water inlet valve for continuity, using a multitester. If there is no continuity, replace the solenoid, if there is continuity, clean the valve filter or replace the diaphraghm. To disassemble the valve, first turn off the hot water supply and drain the two hoses into a pan. Then unscrew the valve from its mounting bracket and detach it from the water connections. To clean the filter screen, unscrew the mounting bracket from the valve body, remove the filter screen and run water through it. Check the flow washer for wear and replace it if necessary. Then unscrew the solenoid from its mounting and run water through the valve body.
Repairing a drain valve.
Test the drain valve solenoid for continuity in the same way as in a water inlet valve; then remove the valve to examine its mechanical parts. First bail out any water standing in the dishwasher tub, then unscrew the valve from its mounting bracket. If the valve resembles the one shown here (inset), pull back the plunger to see whether the rubber seal opens freely. If the seal sticks or is clogged, unscrew the valve body from its solenoid assembly and flush the valve body with water.If the seal is deteriorated, replace the valve.If the drain valve resembles a water inlet valve, repair it as you would the water inlet valve.
Checking Overflow Controls
Repairing a float or pressure switch
Jiggle the float up and down in its sleeve, and pull it out of the sleeve to clear the shaft of any impediment to its movement. If the float moves freely but water does not enter the machine, or if it overflows, turn off the power to the dishwasher at the main service panel, bail out any water in the tub and remove the bottom access panel. Test the float switch terminals (top inset), located under the tub, for continuity. If there is no continuity, replace the switch by unscrewing the retaining nut and lifting the switch off its mounting; screw on a new one.
What to Do When Dishes Do Not Dry
Replacing the heating element.
With the power turned off, remove the lower access panel, disconnect the leads to the heating element terminals and test the element for continuity, using a multitester; if there is no continuity, the element is defective. If the test does show continuity, check the element for a short circuit by touching one probe of the multitester to a terminal and the other to the element's sheath; in this test, continuity indicates that the element is short circuited. To replace a damaged element, remove the bottom access panel and detach the leads from the nuts under the tub (inset) that hold the element in place. Unscrew the nuts and remove any sealing gaskets. Then unhook the element from the fasteners that hold it in place inside the tub, and remove the heating element along with the gaskets that seal its mounting holes.
Repairing a blower heater
With the power off, remove the bottom access panel and detach the wires to the terminals of the motor, the thermostat and the heating element. Test each pair of terminals for continuity with a multitester; any part that does not show continuity is defective. Test for a short circuit in the heating element by touching one probe of the multitester to a terminal of the element and the other to the mounting bracket; if there is continuity, the element is short circuited.
Isolating Control Troubles
Testing the door latching mechanism
If the machine does not start, turn off the power at the main sen/ice panel and remove the control panel to expose the latch and its switch. With the door closed and locked, disconnect the wires on the latch leading to the switch terminals in this case located behind the latch and test the terminals for continuity. If there is no continuity, replace the switch. If there is continuity, the switch is operating, but the latch may not be hitting the strike. Unscrew the retaining screws and adjust the position of the strike, pulling it out until it hits the interlock lever when the door is latched; then tighten the retaining screws, securing the strike in position.
Testing the cycle selector and timer
With the power turned off, remove the control panel, exposing the mounting plate to which the selector and timer are attached. Examine the wires connected to the terminals of the timer and the cycle selector switch. If any terminal is burned or the wire insulation is discolored, replace the entire timer or selector switch, making a diagram to record wire locations as you disconnect the wires. Unscrew the bracket that holds the selector switch against the mounting plate, and slip the switch out of its opening. Remove the screws that hold the timer against the plate. Install a new switch or timer, reconnecting the wires and repairing any that may be damaged.If the wires and terminals are sound, check the switch terminals for continuity. If the switch is defective at any setting, replace it.
Most Common Problems With Dishwashers
The Special Problems of Portable Washers
Portable dishwashers, once more common than the built in variety, work in the same way as their under counter cousins. But they have extra parts that may present special problems: casters that can stick, for example, a retractable electric cord that may not rewind, or a faucet coupler that can leak.When a portable does not roll easily, spin the casters to see whether they turn. Clean a dirty bearing with a damp cloth and lubricate it with light oil; replace the entire caster if the tire is split, if the caster does not swivel, the shank may just need tightening; if the shank is bent, replace the entire caster.
The parts of a leaky faucet coupler assembly that can be replaced separately are the washers and adapters that connect the head to the coupler. If the coupler leaks anywhere along its two hose lines, the water inlet hose or the coupler must be replaced. To replace the coupler, remove the top from the machine and tip it over on its side.
Disconnect the drain hose from the pump and the fill hose from the water inlet valve. Set the machine upright and remove the hoses. Then feed the hoses of a new coupler into the machine, threading them through the hose guides. Once again turn the dishwasher on its side, and reconnect the hoses.
Nice post Double ridged components
ReplyDeleteThanks so much for sharing this information with online! When any oven repair fails to heat the meal well, its atomizer ought to be replaced. This will be easily completed by a homeowner via a screwdriver to eliminate the heating elements from oven's lower and upper walls.
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