Water Drain or Fill Problems - Appliance Repair DIY

Dishwasher Drain and Fill Problems

You can hear fill water constantly flowing
The tub overflows
The tub fill is low, or it doesn’t fill with water

The tub is constantly draining during a wash cycle
The tub doesn’t drain

Fill and Drain Problems
What symptoms are you experiencing?
- You can hear fill water constantly flowing
- The tub overflows
- The tub fill is too low, or there's no water in the tub at all after a fill
- The tub is constantly draining during a wash cycle
- The tub doesn't drain
Water Fill Cycle and Water Level Control

The dishwasher uses a solenoid water valve to allow water into the tub. The tub should fill to a level just below the water heater.
Normal house water pressure is above about 20 psi; the solenoid valve is engineered to deal with normal pressures. If the water pressure is below that level, less water will enter during the fill cycle.

In MOST dishwashers, water level in the tub is controlled by the time that the solenoid stays open, which itself is controlled by the timer. The higher the water pressure, the higher the water level in your tub.

Some dishwashers use a diaphragm air pressure switch to control the water level. Water in the bottom of the tub applies pressure to an air pocket at the diaphragm. The air is compressed, which flexes a diaphragm, and when the pressure is high enough, the diaphragm opens the fill switch, which closes the solenoid.

There is a float switch inside the tub, but it does NOT control the fill level. It is safety switch; if something in the fill system fails, it prevents the tub from overfilling. Think about it...if water is being jetted around inside the dishwasher, the water level will be bouncing the float around, and the water fill switch would be flicking on and off WAY too often.
Underfill; Low or No Water Level

There is a screen in the water valve inlet to strain out any rust or other debris that may be in your water supply. Typically, if the fill pressure is too low, this screen is blocked.

Access the valve as described below and clean out the screen. Do not remove the screen; if it is badly clogged, replace the valve.

If your house just naturally has very low water pressure, you can get a special fill valve that will adapt to your low water pressure.

Another cause is that the water valve solenoid itself might have failed. To test it, test the voltage at the solenoid during a fill cycle. If you have voltage, the valve is probably bad.

If there is NO voltage to the valve during the fill cycle, there are two possibilities; either the timer is not sending voltage to the valve, or more likely, there is a problem with the float switch.

The way I diagnose this is to first remove the float itself, and make sure it is not stuck in place by soap buildup or other debris.

Then test the switch with a multimeter. If you don't know have one or don't how to use one, click here.

If both the float and switch are OK, and you still don't have voltage to the solenoid valve, the problem is likely the timer. Replace it.
Overfill or Flooding
The overfill float switch only works when the dishwasher is turned on.

If the dishwasher is NOT turned on, a leaky water fill solenoid valve will allow water to keep coming in.

If the dishwasher keeps filling during a wash, the overfill float switch should stop it. If it doesn't, it means one, or more, of three possible problems.
- The water valve is leaking or stuck open.
- The overfill float switch is stuck in the closed position.
- Since the timer is what tells the valve when to open, the timer could be malfunctioning.
- If you have a diaphragm pressure fill switch, it could be defective, or the air hose leading it could have a leak.
Test the voltage at solenoid with a multimeter while water is flowing through the valve. If you don't know have a multimeter or don't how to use one, click here.

If there is no voltage, the valve is stuck open. Replace it.

If you have voltage after the fill cycle, the timer, overfill switch and/or float are probably bad, and should be replaced. The diaphragm pressure switch or hose could be bad, too.

If both the float and switch are OK, and you still don't have voltage to the solenoid valve, the problem is likely the timer. Replace it.
How to access the water valve and float switch:

First, UNPLUG THE DISHWASHER or TURN OFF THE BREAKER.

Remove the kickplate and look beneath the dishwasher. You should see the water solenoid valve right up front. If you cannot see well enough under there, it often helps to remove the door panel, too.

To make your electrical tests, you can plug the dishwasher in briefly. Work with extreme caution, and make sure you unplug it again as soon as you're done testing.
Water drain cycle

After a wash or rinse cycle, there are several different ways the dishwasher may drain.

Some dishwashers have a separate drain pump. To drain, the pressure pump stops and the drain pump starts.

In some older dishwashers the motor reverses. In these machines, a second pump is built into the pump body. When the pump motor reverses, the drain pump pushes water out of the tub.

Some older GE dishwashers have a solenoid-operated "flapper" or diverter valve. During a drain cycle, this valve closes off the water flow to the spray arms and diverts it to the drain hose.
Drain Blockage
Blockage of the drain system

Determining where there's a blockage in your drain system is a process of elimination. The most common areas are:
- The drain hose and air gap
- The dishwasher's drain pump, diverter valve, internal filtration system and water passages
Drain Hose and Air Gap
Checking the drain hoses for clogging involves removing them from their connection to the air gap or the house's drain system, and checking for debris clogging the hose or barb fitting.

If you have an air gap in your system, start by checking that. It's a common place for clogging to occur, and pretty easy to get to.

The Air Gap

All the appliances in your house that use water have (or SHOULD have) anti-siphon protection.

Waste water from your dishwasher drains to a sewer system. If water fills the drain hose completely, with no place for air to enter the drain, it IS possible for effluent to siphon from the sewer back into your dishwasher. Yuck, right? Doesn't happen often, but it HAS happened.

To prevent this, your dishwasher has an anti-siphon device called an AIR GAP, installed in the drain hose.

It is required by law in most installations. It prevents accidental backflow (siphoning) into the dishwasher from the house drain lines. A typical air gap re-directs water 180 degrees, and thus it has constrictions that can easily trap a chunk of food trying to pass through it.

Symptoms are the same as for any other blockage of the drain line, except that you may also see water flowing out of the air gap vents directly onto the countertop or into the sink.

Fortunately, they are pretty easy to open and clean. In most installations, it is a little chrome or brass blob with a couple of vent holes in it, sitting right next to your sink faucet handles. If it's not there, find the hose that drains your dishwasher into the sink trap or garbage disposal, and trace it back directly to the air gap.

Usually all that's involved in cleaning it is to pull off the little chrome blob and unscrew the top of the air gap itself. Both drain pipes will be exposed. Often you will find a seed or broken glass, or other bits of food wedged in there.

If the air gap isn't clogged, then it might be where the drain hose enters the house's sewer system. Disconnect the hose to the drain or garbage disposal and root around in there with a screwdriver to see if the drain is clear. If you've just recently installed a new garbage disposal, make sure the knockout is knocked out.
- I don't think the drain problem is caused by the air gap or drain hoses. What do we try next?
If the problem seems to be within the machinery of your dishwasher, you will need to open up the tub components, clean out the water filters and check the water passages.

Click here to go to that section of this website.
If the drain system is running constantly while the dishwasher is running, there are two possible problems.

Some late-model machines have a drip pan built-in with a float sensor in it. If this float switch senses water in the drip pan, the drain pump will run continuously, until the water is removed. Click here to go to the Pump & Motor page.

Some machines have ball check valves to control the drain. The check ball can get jammed, causing the dishwasher to drain continuously. If yours does, you will need to open up the tub components, clean out the water filters and check the water passages. Click here for the Water Filter cleaning page.

In older GE machines with a flapper" (diverter) valve, the flapper can get stuck. In this case, the machine may spray water through the spray arms, until it runs out of water (because it's draining at the same time.) You need to remove the pump and repair or replace the valve or motor assembly as appropriate. Click here to go to the Pump & Motor page.
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