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LG DLE7177RM electric dryer Not Heating


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9 replies to this topic

#1 Andrew Barilla

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Posted 25 March 2011 - 11:57 AM

I have an LG DLE7177RM electric dryer which stopped heating up. I replaced the heating element and it worked for 5 days just fine and now it's not working again. It runs fine, the control panel works and it runs the specified amount of time (my wife only does timed cycles) but it just doesn't heat.

I checked and it is getting 240 volts and I followed the tests in the service manual but to the best of my ability I can't find what's wrong with it.

I figured it's probably one of two things:

1) I just got a bad heating element that died after a week

2) Something else is blowing the heating element.

The one thing that didn't match with the service manual is that the resistance across terminals 2 and 3 is 40 ohms and not less than 9-11. However, it was like this when I got the new heating element before I installed it. I chalked this up to human error and it being almost 20 years since I used a multimeter in physics class. Also, the thermostat in the middle is reading 0 ohms and the one closest to the back is reading a really low resistance. The manual says that they should both be under 1 ohm, but should the one be 0?

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#2 Andrew Barilla

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Posted 25 March 2011 - 12:01 PM

Oh, and I did make sure the vent is clear and even ran it without it attached to the wall at all just to triple check.

#3 RegUS_PatOff

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Posted 25 March 2011 - 12:41 PM

... The one thing that didn't match with the service manual is that the resistance across terminals 2 and 3 is 40 ohms and not less than 9-11.
I chalked this up to human error

... the thermostat in the middle is reading 0 ohms and the one closest to the back is reading a really low resistance.
The manual says that they should both be under 1 ohm, but should the one be 0?

1) Human error, yes, the manual should read:
1 - 2 should read about 20 OHMs
1 - 3 should read about 20 OHMs
2 - 3 should read about 40 OHMs

2) in my physics class, 0 is less than 1 OHM ... :whistling:
in theory, any closed switch or fuse should read 0 OHMs

There's (3) Thermostats (one on the Blower Housing)
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#4 Andrew Barilla

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Posted 25 March 2011 - 12:54 PM

Thanks. I didn't check the one on the blower housing.

#5 RegUS_PatOff

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Posted 25 March 2011 - 01:10 PM

Thanks. I didn't check the one on the blower housing.

never mind, that Thermostat would stop the Drum Motor
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#6 Andrew Barilla

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Posted 25 March 2011 - 11:55 PM

Thanks for the help. My wife talked to a friend of a friend who does repairs and he said that it sounds like I checked everything out except for that one thermostat on the blower housing, which you've mentioned was irrelevant, so that falls back to probably a problem with the PCB which is apparently not all that unusual for LG.

Oh, and the reason I questioned the 0 reading is because my multimeter also reads 0 if you don't touch anything. Now that I'm more awake and more with-it I double checked by also checking for continuity.

#7 john63

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Posted 26 March 2011 - 01:14 AM

HEATING ELEMENTS in LG dryers **rarely** fail.

Unless-----the *exhaust vent* from the rear of the dryer-to-the-outside-venthood is/has been blocked/restricted for a very,very long time.
Even then---the Heating Element usually does not fail.

I've replaced perhaps **one** Heating Element in nine years.

On the other hand---THERMAL LIMITERS will & do fail if the *exhaust vent* is blocked/restricted.
If the *exhaust vent* is a very short-length (1 to 3 feet)---then the liklihood of the vent causing a failed THERMAL LIMITER is nil. The 2nd most common cause of *failed* THERMAL LIMITERS is from Fabric Softener Sheets. Once-in-awhile the Fab. Soft. Sheet will become "caught/sucked" onto the LINT FILTER HOUSING and this causes a giant reduction in AIR FLOW.
Air movement from the Heater-Through-The-Laundry-Through-The-Lint-Filter-And-Exiting-The-Dryer-Exhaust-Vent slows to such a reduced a level---which then causes the Heater Housing Temperature to "spike". This in turn causes the THERMAL LIMITER to *shut-down* the Heater--for safety.



When I get an LG electric dryer that has a NO HEAT complaint--the very first thing that I will examine/rule-out will be the *exhaust venting* that runs from behind the dryer to the outside dryer vent hood. If the vent has been verified 100% to be absolutely-positively clear/unobstructed---and...

1) The wall receptacle has 220 volts

***Unplug the Dryer at this point***

2) The TERMINAL BLOCK is not damaged/burnt (this is where the dryer plug attaches to the dryer)

Then it's time to inspect the THERMAL FUSE. This is centrally-mounted on the side of the HEATER HOUSING.
If the THERMAL FUSE (6931EL3003D) has failed a *continuity* test using a Digital MultiMeter (DMM)--it should be replaced along with the THERMOSTAT (6931EL3001E) which is also mounted on the HEATER HOUSING.

If the THERMAL LIMITER tested "good"...

Place the test leads into the Motor Connector/Plug. One test probe into each of the two *thickest* wires of the Motor Plug.

Looking at the Motor---you'll notice a *black ring* on the motor shaft directly opposite the Motor PULLEY.
This *black ring* is part of the CENTRIFUGAL SWITCH on the Motor (prevents the Heater from functioning if the Motor fails to start).
Use your finger to slide the *black ring* towards/in the direction of the BLOWER WHEEL (it'll slide about 1/2 inch).
At this point the DMM should show *continuity*. If not--replace the MOTOR.

If the CENTRIFUGAL SWITCH tests good---replace the MAIN BOARD (a rare failure for a NO HEAT condition but not impossible).

Edited by john63, 26 March 2011 - 10:04 AM.

To eliminate:

Musty odor

L-O-N-G cycle times

Dingy/yellowing whites

Suds error message

Slow spin speeds

Intermittent water leaks (from rear of washer)

And other annoying symptoms which vary brand-to brand.

Read below:

The *correct* amount of HE (High Efficiency) detergent that should be used in any front load or agitatorless top load washer with tub sizes 3.0 cu ft and larger is as follows:

HE: (2) Tablespoons Per Wash Load

HE 2X: (1) Tablespoon

HE 3X: (1) Teaspoon

Perform a TUB CLEAN CYCLE every (4) months.

Use: "Tide Washing Machine Cleaner"

#8 RegUS_PatOff

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Posted 26 March 2011 - 03:45 AM

... my multimeter also reads 0 if you don't touch anything

are the probes touching each other ?
... closed circuit / closed switch / closed Fuse ...
.

one of my video productions: “Easter Seals: Walk With Me”

every day is Down Syndrome Awareness Day
"A Child Is Waiting" . Burt Lancaster . Judy Garland . 1962

RegUS_PatOff > www.youtube.com/watch?v=oPAY2LsKVEw

#9 Andrew Barilla

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Posted 26 March 2011 - 11:36 AM

HEATING ELEMENTS in LG dryers **rarely** fail.

Unless-----the *exhaust vent* from the rear of the dryer-to-the-outside-venthood is/has been blocked/restricted for a very,very long time.
Even then---the Heating Element usually does not fail.

I've replaced perhaps **one** Heating Element in nine years.

On the other hand---THERMAL LIMITERS will & do fail if the *exhaust vent* is blocked/restricted.
If the *exhaust vent* is a very short-length (1 to 3 feet)---then the liklihood of the vent causing a failed THERMAL LIMITER is nil. The 2nd most common cause of *failed* THERMAL LIMITERS is from Fabric Softener Sheets. Once-in-awhile the Fab. Soft. Sheet will become "caught/sucked" onto the LINT FILTER HOUSING and this causes a giant reduction in AIR FLOW.
Air movement from the Heater-Through-The-Laundry-Through-The-Lint-Filter-And-Exiting-The-Dryer-Exhaust-Vent slows to such a reduced a level---which then causes the Heater Housing Temperature to "spike". This in turn causes the THERMAL LIMITER to *shut-down* the Heater--for safety.



When I get an LG electric dryer that has a NO HEAT complaint--the very first thing that I will examine/rule-out will be the *exhaust venting* that runs from behind the dryer to the outside dryer vent hood. If the vent has been verified 100% to be absolutely-positively clear/unobstructed---and...

1) The wall receptacle has 220 volts

***Unplug the Dryer at this point***

2) The TERMINAL BLOCK is not damaged/burnt (this is where the dryer plug attaches to the dryer)

Then it's time to inspect the THERMAL FUSE. This is centrally-mounted on the side of the HEATER HOUSING.
If the THERMAL FUSE (6931EL3003D) has failed a *continuity* test using a Digital MultiMeter (DMM)--it should be replaced along with the THERMOSTAT (6931EL3001E) which is also mounted on the HEATER HOUSING.

If the THERMAL LIMITER tested "good"...

Place the test leads into the Motor Connector/Plug. One test probe into each of the two *thickest* wires of the Motor Plug.

Looking at the Motor---you'll notice a *black ring* on the motor shaft directly opposite the Motor PULLEY.
This *black ring* is part of the CENTRIFUGAL SWITCH on the Motor (prevents the Heater from functioning if the Motor fails to start).
Use your finger to slide the *black ring* towards/in the direction of the BLOWER WHEEL (it'll slide about 1/2 inch).
At this point the DMM should show *continuity*. If not--replace the MOTOR.

If the CENTRIFUGAL SWITCH tests good---replace the MAIN BOARD (a rare failure for a NO HEAT condition but not impossible).


I think the vent was blocked originally, I was blowing it out with a leaf blower and at one point there was a significant change of pressure. As of right now there's a very obvious air flow from the outside. Also during the whole process I went through the vent system within the dryer and it's now clear. There wasn't anything blocking it but there was quite a build up of lint.

Well I already replaced the heating element and then it worked for about a week. The new thermal fuse did fail the continuity test now that the dryer stopped working. So I'm wondering what might be the problem if nothing is blocked, but the thermostat died again? Or did I just get a bad heating element?

#10 RegUS_PatOff

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Posted 26 March 2011 - 01:28 PM

... The new thermal fuse did fail the continuity test now that the dryer stopped working.

usually an indication of a Vent problem

Dryer Vent

Vent should be rigid metal.
Short lengths of flexible metal may be OK, if not crimped when moving the Dryer into place.
NO plastic
NO PVC
NO screws
Foil Duct Tape is OK.
With an empty load, Timed Dry, High Heat, the vent temperature should cycle somewhere between 135F and 160F
Check / clean the Dryer Vent
Disconnect the Dryer Vent and check for good air-flow there and where it exits the house.
Check the Vent air temperature at the back of the Dryer.
 


.

one of my video productions: “Easter Seals: Walk With Me”

every day is Down Syndrome Awareness Day
"A Child Is Waiting" . Burt Lancaster . Judy Garland . 1962

RegUS_PatOff > www.youtube.com/watch?v=oPAY2LsKVEw






Recent blog entries on this topic

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Troubleshooting tips for LG electric dryers that won't heat

By Samurai Appliance Repair Man in Samurai Appliance Repair Man's Blog, on 26 March 2011 - 04:54 AM

Sublime Master john63 is The School's resident LG and Samsung expert and offers these troubleshooting tips for LG electric dryers that won't heat gleaned from actual hand-to-hand combat with these machines.


HEATING ELEMENTS in...

Read Full Entry →

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