not enough water in dishwasher

aiallegaDecember 27, 2010

I have a Kitchenaid dishwasher and lately the dishes have not been getting clean. I had a repairman out and found that there wasn't enough water getting into the dishwasher during filling (timed fill). He said he could not find a reason within the dishwasher and said he thought our water pressure was not sufficient. For some reason while he was here our pressure did seem to be slightly low (throughout the house). (Of course since then the pressure seems to be fine!). He recommended we have a plumber come out.

I am a little hesitant to call a plumber now since the pressure seems fine. I still have dirty dishes. Is there anything a plumber can do to check or help the water pressure to the dishwasher? What should I do?

Thank you in advance for any help.


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I assume you've looked inside the dishwasher and seen that the water level is not correct. If that's true, and assuming water pressure nominal, I'd look to the fill solenoid. Little devil's frequently fail on their own resulting in incomplete fills. They usually don't make any noise or exhibit any other symptom than incomplete fill. Cheap and easy replacement, if that's the culprit.

Other common reason for unclean dishes are inoperative heater and obstructed drain lines and filters. All easy to check.

    Bookmark   December 27, 2010 at 5:48PM
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PS to previous.....I'm not there, OK, so I don't know, but.....

I don't buy the water pressure diagnosis. Anything between 35-80psi should be fine. I have little doubt it's something else and probably something easy to diagnose and fix. DW's are not complicated machines. I'm disappointed in your "repairman". Did he even measure your water pressure or did he just guess and toss it out there to pacify you? Pressure gauges are cheap, common, and easy to use. He should have had one and used it before speaking.

    Bookmark   December 27, 2010 at 6:23PM
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Thank you asolo!

One thing I noticed is that he never removed the bottom panel to check anything. I'm assuming that is where the electrical components are. He did not measure the water pressure. He basically just checked the filters. I guess I'll call them back out (Sears) and have them specifically check the fill solenoid. I do at least have a 90 day guarantee. Thanks again.

I agree once he saw the slightly low water pressure he quit. arrrrhh

    Bookmark   December 27, 2010 at 8:20PM
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There are a number of things he could have done within five minutes that would have told him -- and YOU -- exactly what the problem is and you'd be solved or well on the way to solving -- cheaply -- the issue.

If the machine is new with 90-day satisfaction deal (I didn't know that) don't take any prisoners. The sequence of events you've described has "stupid tech" written all over it. Your "repairman" was an amateur. Tell them to send out an experienced tech and they'll have you right in 1/2 an hour. If they don't, queer the deal on the spot and have them take the machine back with them. You've not been treated well.

I repeat.....DW's are pretty simple machines. There isn't much to look for. Their guy said "water pressure" and left....without actually checking a damned thing. I would advise being pretty severe with whomever you talk with next. They sent you a lightweight.

    Bookmark   December 27, 2010 at 9:10PM
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It's not a new machine-about 6 years old. The 90 day guarantee is on the service call. I really appreciate your help.

    Bookmark   December 27, 2010 at 10:23PM
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That statement about water pressure is rediculous. While the IRC sets the minimum water pressure at 40psi, under the UPC the code minimum is only 15psi and the dishwasher manufacturer has to build their appliances to work under both codes, therefore that dishwasher should fill the tank correctly even if your water pressure is only 15psi and I am willing to bet if your water pressure was only 15psi you would be here complaining about more than just the dishwasher.

Before you call anyone, there are a couple things you can check on your own.

Start the dishwasher and wait till the fill cycle is complete and it moves to the wash cycle, then stop the machine, open the door and physically see what the water level is. If the water level is low it will result from either a problem with the float switch or the water solenoid valve.

Code maximum water pressure is 80psi so in order to design a machine that will work in all applications they have to design a fill system that will work in a range from 15psi to 80psi. In order to achieve that goal they begin by determining how long it would take to properly fill the tub at 15psi and use a timer that would allow that time (typically 5 to 7 minutes.)

Obviously if the pressure is higher the tub would fill quicker so they need a means of measuring the water level to turn off the fill valve when the tub is full.

In the bottom of your dishwasher you will see an inverted plastic cup about 3" in diameter which is called the float switch cup (see owners manual).

Under that float there is a small diameter plastic standpipe coming up from the bottom of the tub and there is a long plastic rod on the underside of that cup that goes down through that tube. Underneath the tub there is a single pole normally open micro switch that has a short lever attached to it. When the tub is empty the rod from the float cup rests on that arm and holds the switch in the closed position so the energy from the timer will go to the water fill valve. As the water level in the tub rises that float will rise with it and when the float rises up to the full position the float switch opens, thereby turning off the water fill valve.

Lift that float switch cup upwards and it will easily come out. Now look at the underside of the cup. Very often those cups get coated with cooking oils, grease and debris which adds weight so the cup does not float as high as it should. Normally that would cause it to overfill the tub, but under rare circumstances the cup gets filled up with grease and it floats higher, which results in prematurely shutting off the water supply. Solution- remove the cup occasionally and clean it.

The internal orifice in the water fill valve is tiny. Normally when the water level is low the problem results from lime or mineral scale buildup on the fill valve orifice. Years ago we could get a water valve rebuild kit for $1, but such is not the case today. In today's world the solution is to change the water valve, but not to worry, that is a very basic DIY job.

Unplug the dishwasher and turn off the water supply line at the source.

Remove the bottom front kick plate and you will generally find the fill valve right behind the kick plate on the lower left hand side.

There are two wires attached to the fill valve solenoid. (Usually a simple plug). Disconnect those wires.

On one end of the valve you will see a small plastic water line from the valve to the machine held on with a simple hose clamp. Remove that hose.

You will now see two screws that mount the fill valve to the frame of the machine. Remove those screws and carefully pull the valve forward. You will see a brass nut on the back that holds the water supply line on the valve. Unscrew that nut, remove the valve, then reverse the procedure to install the new valve.

I have made a simple diagram to show you how the float switch works....

    Bookmark   December 28, 2010 at 2:43AM
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Majority of dishwashers are timed-fill. The float mechanism usually is overfill protection in case of incomplete drain, not to control the normal fill level.

I've never seen a dishwasher with a 5 to 7 minute timed fill. 1.5 to 2 mins is the usual, one or two increments a mechanical timer depending on how it's geared. Water flow rate is compensated against various mains pressures by a small-orifice flow-washer in the valve, similar to what's used in low-flow shower heads.

    Bookmark   December 28, 2010 at 9:42AM
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lazypup and dadoes,

Thank you so much for the great info.

lazypup, I'm an old lady and although I do the majority of my own repairs around the house I feel that this one is over my head. I have a repairman scheduled to come today and at least now I am MUCH more informed about the problem.

I'll let you know how it goes. Amy

    Bookmark   December 29, 2010 at 1:46PM
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lazypup and dadoes,

Thank you so much for the great info.

lazypup, I'm an old lady and although I do the majority of my own repairs around the house I feel that this one is over my head. I have a repairman scheduled to come today and at least now I am MUCH more informed about the problem.

I'll let you know how it goes. Amy

    Bookmark   December 29, 2010 at 2:32PM
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I don't know why the above posted twice! Well, the repairman found a failing water valve. The valve totally went bad while he was checking it and water started to fill the DW with the DW turned OFF! So we narrowly escaped a flooded kitchen. The part had to be ordered. The water is turned off to the DW at present. Dishes by hand for a week or so. Thanks again.

    Bookmark   December 29, 2010 at 8:42PM
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    Bookmark   December 29, 2010 at 8:58PM
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