Author Topic: LG Gas Dryer DLG2524W Error code 19:HO / U01: Unit spins, but no heat. Help?  (Read 2201 times)

Offline basnap

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Hi All,

Just got married and the wife is pissed already... Dryer stopped heating on any program overnight. The unit is a GAS powered 7 y/o LG DLG2524W. Nothing changed/moved. It spins, completes all programs but it simply does not heat.

There is enough ventilation, no lint in the filter, no clogging etc. Gas is connected and source pipe goes to water heater too which does work

Found the service manual here: DLG2524W Service Manual

It lists some self tests (press 'more/less time' icw 'power'). Then you hit START button a couple of times for different tests, but it never gets that far. Mine circles between 19:H0 and U01 and that's it. Nothing happens when I hit START to perform the other tests. Obviously this error code isNOT listed in the manual.

Found one post where it turned out to be a faulty flameswitch flame switch/sensor

Found another one where the main board was suspected (unconfirmed) Faulty board?

I've opened the unit & performed the following tests:

1) Measured thermostat (M220) and hi limit thermostat (M230) both showed 0 Ohm -> Should be OK
2) Based on 'Gas valve test'* I replaced the M230 but no change
3) Measure resistance of ignitor and flame sensor, both are 0 Ohm -> should be OK
4) Measured resistance of both GAS valve coils (disconnect terminals), both are in the 1150-1180 Ohm -> should be OK

Removed the front panel which holds the door while leaving DOOR switch connected. The drum is still in place and can rotate. And indeed, if I start the unit it will spin. The ignitor will glow deep orange for a few seconds before switching off again, it tries again in a couple of minutes but the gas never fires. I do not hear any clicks on the GAS valves.

This is someone's video where you see how the firing sequence works, but in his case the gas keeps flowing with ignitor off, which is very dangerous. Hard to judge by the video, but his ignitor seems whiter, whereas mine is a deep yellow/orange.




I measured the voltage in both AC and DC (the manual/forums are unclear on AC or DC) of the 2 terminals connecting to the GAS VALVES and I never get above 1 volt. Disconnecting mains will bring this to 0 completely.

Some questions I had.
1) What/who controls the voltage on these terminals?

2) At what stage to expect the voltage to be [ 40 - 90 Volts AC/DC ]?

a) With the unit plugged in but not powered up?
b) With the unit powered up but no program selected
c) When a program is running
d) When a program is running and the ignitor glows?
e) With a program running with actual wet clothes in the dryer such that the moisture sensor detects wetness?

I've measured the power going to VALVE 1 when running a program. Valve 2 is harder to get to but I suppose I could disconnect it. VALVE 1 does show slight voltage change when the ignitor lits up, but again, never reaches anywhere near the 40 - 90 volts I am guessing it needs?

Similar issues with slighty different variations:
Board Defect

Board replacement didn't resolve

Unstable hi limit thermostat

Burner sequence, suggesting 90V should be measurable at coils

Poster also looking for more detailed sequence of what should be measuring at what point

Getting only 20 V on the coils

Long chat, same symptoms, guy replaced board but still 50V

Sorry for this lenghty post. I hope someone can give me some hints. I am suspecting a bad board at this point ($100) but would like to test some more.

Thanks & I will post once resolved


Online tgoods

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Check the wiring between the valve solenoids and the control for continuity. If it checks good, replace the control board.

Offline basnap

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Thanks!

I had done that actually just after the post. from the control board there is one plug with 3 wires, a white, a red and a purple wire.

VALVE1 gets the RED and PURPLE plugs
VALVE2 gets the RED, PURPLE and WHITE

All wires check fine between the COILS and control board.

So next stop... control board....

Offline domain

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Agreed on pcb. We do not have many gas appliances around here, so I do my bestest.  O0

Offline basnap

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I performed one more test. With most of the dryer back together and just the toppanel and the controls not mounted, I ran the dryer while having the plug disconnected facing the 2 GAS VALCES.

I put a volt meter and measured both AC and DC (again, manual says DC but some forums say AC). I do get like .4x Volte and see maybe a small increase when the ignitor glows (which I could see because the top was off).

Hence, the control board doesn't fire to open the valves...  but does that mean control board is bad?

Not in my view... it still could be that *some* sensor tells the control board not to fire because *some* condition is not met.

I did order the part though..

Checked here:

http://www.modelnumberlookup.com/

For my specs (LG, dryer, DLG2524W) and order it off repair clinic. It was a couple of $ more, but since their return policy is great I decided to go with them.

Will keep this thread going till this is resolved satisfactory

Offline domain

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I am 95% sure it is 90 vDC to coils. O0 O0

Offline basnap

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Hi All,

The control board came in, shipped with FedEX and packaged well. It looked the same unit but when I removed the unit from the dryer I was in for a surprise. The newer model is MISSING certain plugs, most notable the 2 for the sensors/thermostat!

I had ordered this unit but my old unit is this one

It turns out that 6871EC1121D was replaced with 6871EC1121A: (The manufacturer or RepairClinic has replaced part number 6871ec1121d with this item, part number 6871EC1121A.)

However:

The newer unit does NOT have plug BL3 NOR the plug for the fire sensor / thermostat but it DOES have an 4 pin extra plug underneath the transformer (no current connector would go connect to that.

Plug BL3 is the EXACT plug I had measured before and it's the one leading to the GAS VALVES. (recall, I was not getting any voltage on the coils so they'd never open).

These are the pins I expect +90 volts on to actually open the GAS VALVES

I fail to see how the valves would ever open when the control plug is not going to be connected on the new board?

I found another website showing the the A part replaces the D part:

http://www.partsdr.com/Parts/6871ec1121a-main-control-board-7158.cfm

I tried there online help:

Chatted with Susan
[Visitor] How are you?
[Visitor] I am looking at this part 6871EC1121A
[Visitor] It replaces this part: 6871EC1121D
[Susan] Good, thanks!
[Visitor] but 6871EC1121D has more plugs
[Susan] Just a minute please.
[Visitor] where does the connector to open the valves get connected to? How will the valves ever open?
[Susan] This part # 6871EC1121A is listed as the proper replacement for part # 6871EC1121D.
[Susan] I do not have any more information than that.


Anyone seen this before? Return it another the Amazon 'D' model?

Offline bagjr387

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I know you went through a bunch of stuff already, sometimes those burner coils can ohm fine, but then when they heat up, they can stop working. If the ignitor glows, and then goes out, its a sign that the coils are weak and need to be replaced. If the ignitor is glowing, then there is power to the gas valve. Unless LG does something way different then other manufacturers, The ignitor is in series with the flame sensor and the burner coils. A glowing ignitor would mean the computer should be fine (unless LG is way different)

Offline john63

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<<<It lists some self tests (press 'more/less time' icw 'power'). Then you hit START button a couple of times for different tests, but it never gets that far. Mine circles between 19:H0 and U01 and that's it.>>>

**********

Software Version Number/Check Digits (normal)

**********

 <<<Nothing happens when I hit START to perform the other tests.>>>

**********

If the TEST MODE will not advance beyond the initial Software Version displayed---failed Main Board.

Correct Main Board is (6871EC1121D) for the LG gas dryer model DLG2524W

The Main Board part number 6871EC1121A is for an LG *electric* dryer model DLE5977


Offline basnap

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@john63: Now that would make sense doesn't it? The electric version would not need to control the gas valves!!!  :) That said, several sites have the 'A' model listed as the replacement for the 'D' model.

@bagjr387: I agree with your assessment, however I was never able to measure any voltage going to the coils. They Ohmed out OK, but never received a voltage. Which leads me to believe that the controller is bad OR that another sensor prevents the controller putting any voltage on...

Ordered the 'D' piece of amazon. Will update once I install it.

Offline bagjr387

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The flame sensor would prevent voltage from going to the coils if it was bad. If you read no voltage to the coils, you have to start running backwards...The flame sensor should have infinite ohms when its cold (if I'm not mistaken) The contacts inside(bi metal) should only touch once the ignitor/flame is there to heat it up. If the ignitor is coming on, The flame sensor is all thats left.

The flame sensor is in series with the burner coils...In case you were confused about it

Offline basnap

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@bagjr387: I agree with you... partially...

The flame sensor could indeed be the issue here. I can see it throwing an 'exception'. Such that the control board never sends a voltage to the coils -> preventing the GAS VALVES to open -> no gas -> no heat.

Per the manual:

12. Flame Detect
Measure resistance of terminal to terminal:
Open at 370F ((Maximum)  Resistance value  ∞
Close at 320F                     Resistance value < 1Ω

Measuring the flame detect at room temp yielded a value of 0 (closed) Ohm... whether it would open (infinite Ohms) at 370F remains to be seen of course... never tested that.

BUT the 'open' condition would only occur if the whole thing was heating up which it wasn't. So with the flame detect in it's correct state it should tell the board to open the GAS VALVES by applying a voltage to the coils.

Some mitigating conditions:

A) It could be that the ignitor would heat the flame sensor up to the point where (>370F it would already be open (inifite Ohm) thus telling the control board to keep the valves shut?
B) It could be that the wiring back to the control board was bad and the CB never got the signal?

To your other point: I do not see how the 'coils are in series with the flame sensor', but it could be. In my mind's diagram the coils are independent and an 'end-point'. The thermistors-flame sensor-ignitor-thermostat complex decides if the conditions are right and via the control board a voltage is then applied to the coils opening so the gas can flow. That same thermistors-flame sensor-ignitor-thermostat complex then decides that there is enough heat (370F) and shuts the valves...

But all of this is mere speculation... see next post..

Offline basnap

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Lost my post, will rewrite tomorrow.. Dryer works again..

Offline basnap

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A promised here is my final update. Yesterday I closed out my browser without hitting Post.

The dryer works again! After I replaced the control board (CB) and reassembled it, it ran just fine.

I am still baffled by this as the CB does not have any moving parts to it. More over, the CB is never exposed to the heat/cold like the thermistors and thermostat are. Given that all pieces checked out ok and a replacement board solve the issue, I have to conclude that it was the CB which caused this the dryer to stop working

That said: When I perform the self checks it STILL cycles between the 19:H0 and UO1 error coders! That has not changed. Makes me wonder if it ever worked of whether I am performing the test incorrectly.

Some general recommendations based on my experience:

1) Find forums, read forums, post for help
2) Find the (system!) manual of your model but..
3) Don't get hung up on your specific model. A dryer is a dryer.. a gas dryer is a gas dryer
4) Do the basic checks (power plugged in, vent clear, lint filter clear?)
5) Perform the tests via the CB per the manual

6) When deciding to open the unit get your tools ready first, not special except volt/ohm meter
7) Where gloves! the inside pieces are sharp and heavy. I had to stop working at one point since I got a big gash
8) The unit can spin without the door frame being in place and just the harnass.
9) Do connect the door switch, without that connected nothing works
10) take pictures when undoing a complex part, saved me many times
11) Look up youtube video's for guidance
12) Look at the return policy of the components you buy. I had to return 2 of the ones and that went without an issue.


I made this thread super lengthy because we probably all want to save money in this economy so I tried to document my steps as careful as I could which I hope would be useful. If anyone comments on this post I will see it and will keep an eye on if anyone has a specific question I could help with.

Thank you all who contributed!

I have learned a great deal about dryers :) (I am a Linux engineer by trade)

Believe it or not, on the same day I put the CB in, our Badger 5 SINK ingenerator started leaking... NEXT project!



Offline john63

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<<<am still baffled by this as the CB does not have any moving parts to it. More over, the CB is never exposed to the heat/cold like the thermistors and thermostat are. Given that all pieces checked out ok and a replacement board solve the issue, I have to conclude that it was the CB which caused this the dryer to stop working>>>

**********

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