WM3431HS - dHE Error (cleaned trap, etc)

[moore1289]

Hi Guys,

I have a 10 year old LG WM3431HS.  I got a dHE code. Researched a bit on the internet and found that cleaning the lint out of the duct usually fixes the problem.  Sure enough the duct was caked full of lint.  I cleaned it all out, put it all together and still get the dHE code.

I followed the service manual diagnostics.  Fuse is good, Thermistors are good, Thermostat is good.  Heater is good.  I'm not getting 120VAC at the heater, which the service manual says is the main board.  I bought a new main board, replaced it and still no change...

I've also manually tested the heater by hooking it up to 120V and it works great.  Is there some element I am missing here, or some component that is failed that is causing the main board not to send power to the heater?  I feel like a fuse is blown or something is causing this error.

I've been working on this for a couple of weeks and I'm really close to just calling a service guy.  Part of me wonders if the service guy will have any more luck...

 

Thanks for any help!! -Charles M

[john63]

Does the "dHE" error occur immediately after the cycle has been started...or during the drying cycle?

[john63]

Two common triggers...

1. Red wire on Thermostat gets pulled off by tub assy during spin cycle.

2. Blower motor defective...can be tested in Test Mode....if seized or spins too slow...will eventually trigger "dHE" error. 

Blocked duct does not trigger an error...just takes 6 hours or more to dry clothing.

[moore1289]

The dHE error comes on about 8-19 minutes into the drying cycle.  Occurs regardless if its from a dry cycle only or a full wash cycle into dry cycle.

Checked the red wire on thermostat earlier and its fine (I found an old thread where that was mentioned).

Which mode do I test the blower motor in? "Temperature in Dry Duct", press start/pause 11 times?

The heater does not get hot during dry cycle. 

[john63]

You can remove the screws to the blower motor...then flip the motor over.

The Service Manual has an error in that it fails to specify which test mode activates the Blower Motor.

With the motor exposed/upside down...try test number 11 and after.

Fan motor should be fairly fast (rpm).

If it's sluggish/slow...the Main Board will detect that through a speed sensor built into the motor.

Edited April 16, 2017 by john63

[john63]

Test 11 should be...

Heater on 5 minutes.

Fan motor on 6 minutes.

[moore1289]

So I did this, and it seems that when I do this test (motor upside down) everything works.  Heater works, fan works.  Everything works.  

 

When I re-install downwards, and repeat the test the heater does not turn on...

 

Fan spins really fast, I don't know if its supposed to spin up faster than it currently does or what.  Should I replace the fan motor?

[john63]

With fan motor re-installed...does it run?

If not...replace fan motor.

If fan motor runs...but very labored/slow...replace fan motor.

Heater will not function if fan motor is defective.

[moore1289]

OK Fan is on order. I'll update when I install. Thank you so much for your help.  I'm not sure I could have figured this out on my own.  I feel like the service manual should have had this listed as a diagnostic step...  It jumps straight to the main board, which was costly and ended up being fine.

[john63]

If the Main Board was ordered from either appliancepartspros.com or repairclinic.com...

You can return it for a full refund...minus shipping.

[moore1289]

ordered and installed a new blower, and still getting the dHE error.  Any other ideas on what it could be?

[john63]

Have you inspected/cleaned the Blower Motor Housing?

If there's lint accumulation...that can interfere with the blower motor function (cannot rotate). 

Edited April 21, 2017 by john63

[moore1289]

The Blower motor housing is part of the assembly as I understand it.  The housing is clean as a whistle as is the condensing duct.  The heater area is also clean, and it looks like the duct going back into the drum is also clean, but I cannot verify that its entirely clean as it looks like its more difficult to take apart. From the service manual diagram, it doesn't look like there is much opportunity for it to get clogged there.

I repeated the test where you flip over the blower, and again, it works perfectly.  When I re-install, the heater does not turn on.  I'm really confused as to what is being triggered that is causing it to not send power to the dryer.  Any other ideas?

[john63]

What happens if you (carefully) flip the blower motor over to it's normal installed position...while in test mode?

You can wear gloves for protection...

[john63]

If it stops running...while holding the fan motor with gloves...

Possible wire/plug connection fault.

As far as you can determine...there's nothing in the blower housing...that could be preventing the fan from turning? No obstruction at all?

After re-installing the fan motor to the duct/housing...try moving the fan motor *plug* back and forth to check for weak plug connection (during test mode).

Edited April 21, 2017 by john63

[moore1289]

Yes I tried that last night, and when flipped back over the heater turns off.  Doesn't make any sense to me.  What is causing this?  You said its a speed sensor, but is it an air flow or just motor speed sensor.  Is there an over ride, or a chance that sensor could be bad?

no obstruction in blower housing at all. I don't see how it could be any more clean unless I bought a new one.

 

Is there any sort of master reset for this machine?

Also should I remove the front door and completely clean the rubber gasket/lint traps? Any chance that is impeding the air flow?

 

[john63]

It's not an airflow issue.

The fan motor should have a 3 wire connector.

One of the wires provides signal feedback to the Main Board (rpm).

We definitely have a wire-related problem.

Have you tried moving the plug back and forth (on the motor)?

Gotta think this one over a little bit...will post back....

 

Edited April 21, 2017 by john63

[john63]

When you removed the motor and flipped it over...this twisted the wire harness.

Try unplugging the fan motor plug...twist the plug/wire harness 180 degrees and reconnect plug to motor.

Will the blower run?

[moore1289]

I tried moving the plug back and forth, but no dice.  Do you know where those wires hit the main board? I could try moving that connector as well.

 

Also tried twisting 180 degrees and plugging back in, but it was same result.  Fan blower works great, its just that the heater will not turn on when the fan blower is down and inside the housing.  

[john63]

Another test that can be done is...

Remove the Blower Fan Motor from the duct assy.

Hold blower motor (with gloves)...do not flip the motor over though.

Have a helper initiate test mode.

Does the fan motor attempt to start (slight wiggle)?

[john63]

Our problem is not at the Main Board...since the blower and heater both function only when the fan motor is upside down.

Odd for sure...but a big clue that indicates a problem with power supply or interrupted signal feedback (wire) at the plug or within the wire harness.

[moore1289]

headed to work, Will complete next test when I get home.  What would failure of that test indicate?

 

[john63]

If the blower wheel stutters but does not spin...that would tell us that the signal wire has a problem.

When the Main Board sends power to the blower motor...the rpm signal feedback wire must send the rpm signal back to the board...instantly.

If it doesn't...the power to the fan motor will be shutdown...and lacking a signal...the board will trigger a "dHE" error.

If the Main Board does not receive signal feedback...the heater function will be locked out.

This prevents a "Chernobyl" from lack of air moving through the heater housing.

Edited April 21, 2017 by john63

[john63]

Another thought...

Carefully examine the wire harness from the fan motor plug...down to the cabinet area...check for possible damage to the wiring...that can be caused by a tub-to-cabinet strike (this is unlikely but should be ruled out).

Last test would require a test meter...to test for continuity in each of the 3 wires...from the Main Board to the Fan Motor.

 

[moore1289]

The blower wheel definitely spins, so that is not the issue.

I can check the continuity from the 3 wires to the main board tonight.  I'd be happy to rewire that if it fixes this issue.  This is driving me nuts.  We've been out of a washer for a month!