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Author Topic: Dryer Won't Heat  (Read 30333 times)

Offline TSOL68

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Re: Dryer Won't Heat
« Reply #20 on: May 26, 2010, 04:01:04 PM »

Ok, I just got my new main board and I pretty much have the same results.  Coil 1 gets 120 DCV as ignitor is glowing, then coil 2 has nothing.  However, for about 3 or 4 seconds before the ignitor starts glowing, coil 2 gets 22DCV.

Offline john63

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Re: Dryer Won't Heat
« Reply #21 on: May 26, 2010, 04:24:36 PM »
Ok, I just got my new main board and I pretty much have the same results.  Coil 1 gets 120 DCV as ignitor is glowing, then coil 2 has nothing.  However, for about 3 or 4 seconds before the ignitor starts glowing, coil 2 gets 22DCV.

Follow the wires from the gas coils to the main board.
Look for chaffed/damaged wire(s).

Offline TSOL68

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Re: Dryer Won't Heat
« Reply #22 on: May 26, 2010, 04:38:25 PM »
Ok, will do.  Another thing, I was thinking after reading the service manual; could it possibly be the flame (or as the manual says "frame") sensor?  It seems like that part gives the signal for the main board to open valve 2?

Offline Beehive Appliance

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Re: Dryer Won't Heat
« Reply #23 on: May 26, 2010, 04:51:45 PM »
Has anyone suggested that the ignitor may not be pulling enough amps to open the other coil? I have seen where the ignitor looks like it is working however it doesn't build up enough amperage to open the valve coil. I believe the amperage should be about 3-4 amps and is easily checked with a clamp on amp meter
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Offline john63

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Re: Dryer Won't Heat
« Reply #24 on: May 26, 2010, 05:36:41 PM »
Ok, will do.  Another thing, I was thinking after reading the service manual; could it possibly be the flame (or as the manual says "frame") sensor?  It seems like that part gives the signal for the main board to open valve 2?

If the *contacts* within the FLAME SENSOR are pitted---it can cause erratic burner function.

Offline john63

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Re: Dryer Won't Heat
« Reply #25 on: May 26, 2010, 05:37:33 PM »
Has anyone suggested that the ignitor may not be pulling enough amps to open the other coil? I have seen where the ignitor looks like it is working however it doesn't build up enough amperage to open the valve coil. I believe the amperage should be about 3-4 amps and is easily checked with a clamp on amp meter

This method (amperage) is not used in dryers.

Offline TSOL68

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Re: Dryer Won't Heat
« Reply #26 on: May 26, 2010, 06:09:42 PM »
Ok, will do.  Another thing, I was thinking after reading the service manual; could it possibly be the flame (or as the manual says "frame") sensor?  It seems like that part gives the signal for the main board to open valve 2?

If the *contacts* within the FLAME SENSOR are pitted---it can cause erratic burner function.

Thanks.  That is not my problem right now.  I'm not connected to gas, just trying to get the valves to each get 90DCV.  I'll check the wires tonight.

Offline Beehive Appliance

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Re: Dryer Won't Heat
« Reply #27 on: May 26, 2010, 09:20:37 PM »
Has anyone suggested that the ignitor may not be pulling enough amps to open the other coil? I have seen where the ignitor looks like it is working however it doesn't build up enough amperage to open the valve coil. I believe the amperage should be about 3-4 amps and is easily checked with a clamp on amp meter

This method (amperage) is not used in dryers.
I know that amperage is from a more basic old school dryer, however, the second valve shouldn't open unless there is a hot enough ignitor. It is merely a safety issue. If he has replaced the board, I would check the valves resistance to be between 1500 ohms - 2500 ohms. If these are within spec then I would jump to the ignitor. The service manual says it should measure between 100 - 800 ohms. Another thing to remember, is that when you are taking these measurements make sure the component is unplugged from any wiring.
Beehive Appliance is a family owned appliance repair business in Utah established in 1946. From dishwashers to dryers, we repair it all. If you are looking for expert service at a reasonable price, look no further. Beehive Appliance Service is your solution. Give us a call today! 801-523-8184

Offline TSOL68

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Re: Dryer Won't Heat
« Reply #28 on: May 27, 2010, 12:45:24 AM »
Follow the wires from the gas coils to the main board.
Look for chaffed/damaged wire(s).

Wires appear to be fine.  A red one loops between the two coil plugs, and three wires (red, pink, and white) wrapped in electrical tape are fine to the main board.

Offline TSOL68

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Re: Dryer Won't Heat
« Reply #29 on: May 27, 2010, 12:49:26 AM »

I know that amperage is from a more basic old school dryer, however, the second valve shouldn't open unless there is a hot enough ignitor. It is merely a safety issue. If he has replaced the board, I would check the valves resistance to be between 1500 ohms - 2500 ohms. If these are within spec then I would jump to the ignitor. The service manual says it should measure between 100 - 800 ohms. Another thing to remember, is that when you are taking these measurements make sure the component is unplugged from any wiring.

The valve resistance is 1995 ohms and the ignitor is 185. 

Offline TSOL68

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Re: Dryer Won't Heat
« Reply #30 on: May 28, 2010, 01:23:46 AM »
Did you give up on me already?  :)  Tonight I pulled out the drum and tested everything I could get my probes on, everything is in spec with the manual.  I re-tested valve 2 (pink and red wires) at the plug on the main board....Still not getting any voltage after the ignitor goes out.  Valve 1 (red and white wires) gets 100DCv as ignitor is on.  It seems that the mainboard is not getting the signal to open valve 2, could this be the ignitor not getting hot enough for the flame sensor to open the valve?

Thanks Again!

Offline Beehive Appliance

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Re: Dryer Won't Heat
« Reply #31 on: May 28, 2010, 02:16:31 AM »
This is where it gets difficult. I would lean towards telling you to try the ignitor. Unfortunately everything else seems to be okay. The ignitor has to be just right for the valves to open. It is merely a safety issue. I have seen it way to often on older machines. From reading the posts and the fact that you have replaced the board, I would replace it.
Beehive Appliance is a family owned appliance repair business in Utah established in 1946. From dishwashers to dryers, we repair it all. If you are looking for expert service at a reasonable price, look no further. Beehive Appliance Service is your solution. Give us a call today! 801-523-8184

Offline TSOL68

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Re: Dryer Won't Heat
« Reply #32 on: May 28, 2010, 09:41:48 AM »
Ok, I will try that.  This dryer is very heavily used.  3-4 loads a day, and my wife would even warm up the kid's blankets with it.  So maybe  the ignitor is just not getting hot enough

Offline john63

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Re: Dryer Won't Heat
« Reply #33 on: May 28, 2010, 11:00:56 PM »
The fault is likely the MAIN BOARD.

New parts can be a "dud".

The IGNITER only needs to provide heat for the FLAME SWITCH to "sense" it and to provide a source of ignition of the gas.
Amperage (the gas oven type) has no role in dryer burner ignition.

The gas coils are within specification (ohms).

The MOTOR SWITCH is okay--since the IGNITER functions.

The THERMOSTATS & THERMAL LIMITERS are good---the IGNITER is working.

Generally---when a FLAME SWITCH fails---the IGNITER will not glow or the burner never ignites.

Try replacing the FLAME SWITCH (p/n: 6501EL3001A) as this is not only a possibility but is relatively inexpensive.

If that fails to resolve the problem...

This still leaves the MAIN BOARD & the WIRE HARNESS as the most likely suspects.

« Last Edit: May 28, 2010, 11:20:21 PM by john63 »

Offline TSOL68

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Re: Dryer Won't Heat
« Reply #34 on: May 29, 2010, 10:37:10 PM »
Can I eliminate the wire harness since I tested voltage by inserting my probes into the plug that attaches directly to the main board?  I will order the flame switch on Tuesday.  Thanks!

Offline Beehive Appliance

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Re: Dryer Won't Heat
« Reply #35 on: May 30, 2010, 01:08:00 AM »
Your wire harness is fine. I am attaching a part of a manual which explains how the LG Gas valve flows. The Flame sensor has only a 50 degree spread between open and closed. open @370 closed @350 Have you put an ohm meter on the two leads of the flame sensor while you are trying to run the machine? if so, does it ever open (have no continuity)? this should be open when the ignitor is at its hottest point. I still think you have an issue with the ignitor not getting hot enough or the sensor never opens. One trick you may try is to carefully disconnect  one of the wires to the sensor while the ignitor appears to be heating. Do this with the gas off, and while you are measuring voltage to valve 2. This will tell you if everything above (board, wire harness) is working fine. If you have your voltage at this point you are sure it is either the sensor or the ignitor. I still would try the ignitor first because in my experience the sensors just don't fail that often.

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« Last Edit: May 30, 2010, 01:09:34 AM by Beehive Appliance »
Beehive Appliance is a family owned appliance repair business in Utah established in 1946. From dishwashers to dryers, we repair it all. If you are looking for expert service at a reasonable price, look no further. Beehive Appliance Service is your solution. Give us a call today! 801-523-8184

Offline TSOL68

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Re: Dryer Won't Heat
« Reply #36 on: June 12, 2010, 02:52:37 AM »
OK, I got all of my parts and you are not going to believe this.... I still had the same problem, only 22DCV to the valve 2 plug.  I was about to give up but I decided to put the plug on valve 1 and then test 2 (I was testing with both plugs disconnected) viola!  I have 103DCV.  So I took off each part and tested.  Now I am back to my original equipment and I get 103DCV.  Since the dryer still won't heat, what now?  The gas coils?

Offline Beehive Appliance

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Re: Dryer Won't Heat
« Reply #37 on: June 12, 2010, 09:19:23 AM »
What parts did you end up getting?
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Offline RegUS_PatOff

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Re: Dryer Won't Heat
« Reply #38 on: June 12, 2010, 09:36:03 AM »
 
(I was testing with both plugs disconnected)
voltages are always tested with devices connected, unless otherwise directed.

back to square one ....
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Offline JWWebster

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Re: Dryer Won't Heat
« Reply #39 on: June 12, 2010, 09:59:41 AM »
The valve resistance is 1995 ohms and the ignitor is 185 ohms.  
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