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Author Topic: Dryer Won't Heat  (Read 30339 times)

Offline TSOL68

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Dryer Won't Heat
« on: May 04, 2010, 12:07:23 PM »

Hi all.  I have a DLG3788W that doesn't heat.  I was trying to solve my problem by following an earlier post, but wanted to stay away from the "shotgun" approach.  My dryer symptom is that it doesn't heat at all.  I Tested valve 1 and it peaks at 126VAC when the igniter is glowing.  But after the ignitor goes out, valve 2 only gets 24VAC.  Could this be my problem?  If so, what could be causing this?  Flame dectector? or?  Thank you

Offline john63

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Re: Dryer Won't Heat
« Reply #1 on: May 04, 2010, 01:12:46 PM »
Hi all.  I have a DLG3788W that doesn't heat.  I was trying to solve my problem by following an earlier post, but wanted to stay away from the "shotgun" approach.  My dryer symptom is that it doesn't heat at all.  I Tested valve 1 and it peaks at 126VAC when the igniter is glowing.  But after the ignitor goes out, valve 2 only gets 24VAC.  Could this be my problem?  If so, what could be causing this?  Flame dectector? or?  Thank you

Good diagnostics...

Failed MAIN BOARD
Part # 6871EC1121F

Offline TSOL68

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Re: Dryer Won't Heat
« Reply #2 on: May 04, 2010, 04:18:41 PM »
Thank you for the quick reply.  Are there any diagnostics or tests I can perform on the main board?, just to make sure.  This part is probably not returnable.

Offline whirlpooltech

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Re: Dryer Won't Heat
« Reply #3 on: May 04, 2010, 04:56:12 PM »
If you order from the above link it can be returned.

From the RepairClinic website.

Quote
Return Any Part
Electrical parts? Special-order parts? No problem. We absolutely guaranty your money back if you decide to return a part within 30 days. And of course we'll refund your shipping and handling charges if we select the wrong part for you.
AppliancePartsPros.com - Over 2 Million Appliance Parts In-Stock. 365-Day Hassle Free Return Policy!

Offline john63

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Re: Dryer Won't Heat
« Reply #4 on: May 04, 2010, 07:40:26 PM »
Thank you for the quick reply.  Are there any diagnostics or tests I can perform on the main board?, just to make sure.  This part is probably not returnable.

Your diagnostics isolated the fault.

Valve no.2 should show 90-120 volts from the MAIN BOARD.

Offline RegUS_PatOff

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Re: Dryer Won't Heat
« Reply #5 on: May 04, 2010, 09:43:43 PM »
John63,
Why is it that some LG Dryer Service Manuals mention 90v AC at the Gas Valve Coils, and other LG Dryer Service Manuals mention 90v DC at the Gas Valve Coils ?

With the same Gas Valve part numbers.
After leaving this Earth, "Do you want the smoking or non-smoking section?"

Offline john63

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Re: Dryer Won't Heat
« Reply #6 on: May 04, 2010, 09:56:10 PM »
Hello Regis

Most likely a service manual *typo*. Wouldn't be the first.
I cannot recall that the gas valve coils at one time were DC voltage--but I'll check & verify.

If that is the case--I'll definitely post that information.

John

Offline RegUS_PatOff

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Re: Dryer Won't Heat
« Reply #7 on: May 04, 2010, 10:02:18 PM »
such as
DLG8388 Service Manual = 90v DC

DLG8388 Training Manual = 90v DC
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Offline JWWebster

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Re: Dryer Won't Heat
« Reply #8 on: May 04, 2010, 10:58:22 PM »
If it was dc wheres the inverter?
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Offline RegUS_PatOff

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Re: Dryer Won't Heat
« Reply #9 on: May 04, 2010, 11:02:36 PM »
90v DC ...
 it's called a Diode
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Offline JWWebster

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Re: Dryer Won't Heat
« Reply #10 on: May 04, 2010, 11:08:43 PM »
With the thin wires and dc voltage these coils seem inferior in design, why does LG allow this?
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Offline john63

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Re: Dryer Won't Heat
« Reply #11 on: May 04, 2010, 11:09:48 PM »
John63,
Why is it that some LG Dryer Service Manuals mention 90v AC at the Gas Valve Coils, and other LG Dryer Service Manuals mention 90v DC at the Gas Valve Coils ?

With the same Gas Valve part numbers.


Okay--checking the most recent training manuals has confirmed your sharp observations Regus...

All LG dryer gas valve coil assemblies (part # 5221EL2002A) use 90 volts DC current fed from the MAIN BOARD.

Some manuals did indeed have an *incorrect* (typo) troubleshooting flow-chart listing the voltage incorrectly as AC.

The correct sequence of operation for GAS HEAT operation is as follows:

1) FLAME SENSOR must be *closed* (closes at 320F)

2) COIL no. 01 is energized (90 VOLTS DC)

3) IGNITOR is energized & glows (120 volts)

4) FLAME SENSOR opens (370F) & IGNITOR turns off

5) COIL no. 02 is energized (90 VOLTS )---Flame Ignites.

I may start calling you EAGLE EYES Regus--that's an impressive observation on your part---and a glaring error on my end:)
Good job.

Just to be absolutely certain---I pulled a new GAS VALVE COIL ASSY out of a box to check the label--103 DC.

This means that with a meter set to DC voltage---it should indicate 90 to 103 VOLTS DC  on either coil # 01 or 02.

John

« Last Edit: May 04, 2010, 11:31:44 PM by john63 »

Offline RegUS_PatOff

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Re: Dryer Won't Heat
« Reply #12 on: May 04, 2010, 11:12:38 PM »
With the thin wires and dc voltage these coils seem inferior in design, why does LG allow this?
wire size would be the same whether it was the same AC or DC volts... same current
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Offline RegUS_PatOff

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Re: Dryer Won't Heat
« Reply #13 on: May 04, 2010, 11:16:43 PM »
I may start calling you EAGLE EYES Regis--that's an impressive observation on your part

 :o My eyesight isn't as good as it once was (see RegUS_PatOff)

http://www.youtube.com/watch?v=oPAY2LsKVEw
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Offline JWWebster

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Re: Dryer Won't Heat
« Reply #14 on: May 04, 2010, 11:17:09 PM »
Now  I am totally confused, what electrical measurement is kg's?
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About the icons: The beer is tip link, if a tech saves ya some money buy em a 6 pack. The small green square=personal message. The green dot is a link to my web page on appliance repair

Offline JWWebster

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Re: Dryer Won't Heat
« Reply #15 on: May 04, 2010, 11:25:22 PM »
May the hinges of our friendship
        never grow rusty.

About the icons: The beer is tip link, if a tech saves ya some money buy em a 6 pack. The small green square=personal message. The green dot is a link to my web page on appliance repair

Offline john63

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Re: Dryer Won't Heat
« Reply #16 on: May 04, 2010, 11:25:47 PM »
Hi all.  I have a DLG3788W that doesn't heat.  I was trying to solve my problem by following an earlier post, but wanted to stay away from the "shotgun" approach.  My dryer symptom is that it doesn't heat at all.  I Tested valve 1 and it peaks at 126VAC when the igniter is glowing.  But after the ignitor goes out, valve 2 only gets 24VAC.  Could this be my problem?  If so, what could be causing this?  Flame dectector? or?  Thank you

Courtesy of our friend Regus-Patof--an error in the troubleshooting flow chart has been identified.

Repeat your diagnostics test using the DC scale on your test meter on COILS 1 & 2.

The coils should be getting 90 VOLTS DC (Direct Current).

Sorry for the confusion--post your results...

« Last Edit: May 04, 2010, 11:49:08 PM by john63 »

Offline TSOL68

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Re: Dryer Won't Heat
« Reply #17 on: May 05, 2010, 12:58:36 PM »
Ok, will do.  Thanks for all of the discussion. 

Offline TSOL68

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Re: Dryer Won't Heat
« Reply #18 on: May 06, 2010, 12:33:39 AM »
Ok, retested with DCv:

Coil 1 (top coil) wire gets 100DCV just before, and as ignitor is glowing.
Coil 2 (the one you can reach with just the front cover off) wire gets -26DCV as ignitor is glowing, then goes to 0 until ignitor starts glowing again, then -26DCV

Offline john63

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Re: Dryer Won't Heat
« Reply #19 on: May 06, 2010, 12:43:58 AM »
Ok, retested with DCv:

Coil 1 (top coil) wire gets 100DCV just before, and as ignitor is glowing.
Coil 2 (the one you can reach with just the front cover off) wire gets -26DCV as ignitor is glowing, then goes to 0 until ignitor starts glowing again, then -26DCV

Same result--failed MAIN BOARD.

Good luck.