LG Dishwasher - LDF7551ST

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  #1  
Old 12-08-14, 08:55 AM
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LG Dishwasher - LDF7551ST

Hello,

I have a LG dishwasher 2.5 years old model LDF755ST1, cycle completes then at the end I get an HE code, this means heating element failure. The dishes are all wet and not dry. This model does not have a in the tub heating element so I'm thinking it has to do with the temperature of the water, maybe a heating element that heats the water??? I have no idea where to start or what to look for. I never opened one of these up so I link to a diagram would be great.
 
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Old 12-08-14, 09:28 AM
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Welcome to the forums.

Your model number should be.... LDF7551ST
Your dishwasher use a fan and vent system to dry the dishes called hybrid drying.

From LG.....
What is the hybrid drying system?
The dishwasher does not rely on a heating element for the drying process; instead, it relies on the heat that is retained by the dishes and the tub during the wash and rinse cycles to turn the moisture in the tub into humidity. Warm, moist air in the dishwasher is then pulled into a condensing duct in the door by a fan. The air then cools, which causes the humidity to condense. Room temperature air is also drawn into the duct to help the air cool down faster.
When this moisture condenses into a liquid, it is drained out.

NOTE:
Rinse aid is required to enhance the drying performance. If no rinse aid is used, water may remain on the dishes and the tub.

Make sure the fan is running during drying.
I'm looking into the HE code.
 
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Old 12-08-14, 09:37 AM
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ok will check the fan system....i think this is located in the door...is this pretty easy to open???
How do I check if the fan is running? ohm test, etc???
 
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Old 12-08-14, 10:12 AM
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In the link below, the video shows how to replace the fan in the door but it can also be used for diagnostic purposes.

youtube/watch?v=ZPSK068hZLw#t=117
 
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Old 12-08-14, 10:33 AM
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In checking further I found your unit does use a heating element. I believe it's part of the hot water and steam system.

In the following link, part M081 is the heating element. It should be accessible under the machine in the sump area.

LG Dishwasher Sump assembly Parts | Model LDF7551ST | SearsPartsDirect
 
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Old 12-08-14, 10:39 AM
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ok any advice on how to test the functionality of either the fan or the heating element?

any good video tutorials?
 
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Old 12-08-14, 10:48 AM
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The fan and heating element need to be checked with an ohmmeter. They both only have two wires so it's fairly easy.

Have you ever opened your dishwasher during a wash cycle..... has it been hot inside ?
Have you ever felt hot air come out of the door ?

My thought is the heating element circuit is the problem.
 
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Old 12-08-14, 10:55 AM
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yes to felt the hot air...will check and get back, thank you.

ohm testing, i have a multimeter but will have to reeducate on how it is used...should this be tested with the power out or on?
 
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Old 12-10-14, 08:25 AM
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Hello,

Haven't had a chance to troubleshoot yet...due to long hours at work...but been thinking about it.

Question, I am more leaning to the fan being the culprit...the reason being because the diswasher completes it cycle...like 2 hours. Towards the end, I am given the HE code and all the dishes are wet so makes more sense that it would be the fan motor????

I am also thinking that if it was the heating element the diswasher would not complete its cycle...does this sound like good reasoning....
 
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Old 12-10-14, 08:50 AM
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Good reasoning. When the normal cleaning cycle ends and before the fan would run..... open the door and see if the dishes are hot.

The fan dries the disher by drawing cool air over the hot dishes. If the dishes aren't at least fairly warm... they won't fully dry.
 
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Old 12-10-14, 09:33 AM
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ok...will do that tonight. thank you
 
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Old 12-11-14, 02:23 PM
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ok...went home last night watched video on how to replace fan that was recommended...excellent video by the way...
Turned on dishwasher on quick and dry cycle...1 hour 19 min...midway opened up and was steaming hot, so I suspected heating element was ok.

Opened up again at about 5 min to cycle completion...things still hot, allowed the cycle to complete and no HE codes....hmmm what gives here???

Think we will try to run normal full cycle with dirty dishes tomorrow.

Any suggestions on what is going on???? intermittent electrical issues????
 
  #13  
Old 12-16-14, 12:23 PM
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Hello,

So far no HE codes....this dishwasher has not given me any issues thus far...so I'm crossing my fingers and hoping that it was a fluke...
 
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