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tuc

LG DLE 5977B NO HEAT

9 posts in this topic

The daughter says, dryer no heat - laundry mat sucks.

appliance guru lead me staight to the problem, thermal fuse blown.

must be the vent, flex line a little kinked and some lint build-up.

replaced thermal fuse, cleaned dryer and vent, and replaced flex line. dryer seemed fine when reinstalled, good warm air flow out vent. daughter calls next day no heat!

thermal fuse blown again. when I test the high limit thermostat from the heater assem, it opens at approx.  375f and closes back at 80f. I'm thinking this is too high, part has L125 - 31C on it, guess this should open around 267f.

I've ordered another thermal fuse and a new high limit thermostat.

my question is , does it seem like I'm on the right track or have I missed something

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Need appliance parts? Call 877-803-7957 now!

Dryer Vent 4" diameter

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.

 

Also: make sure there is no heat when the Dryer is set to run in the no-heat (air-fluff) Cycle,

Also: When running a normal heating cycle, make sure the Heating Element doesn't stay ON when the Door is opened.

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thank you for your reply.

I will check the air temp at the rear as you suggest, when I get the parts I've ordered.

and I plan to get rid of the flex and use rigid when reinstalling.

I will also check for no heated air when on fluff, but what is the best way to check the heating element when the door is open?

also I'm a little unclear, is the high limit thermostat on the heater assem. what controls the heater element on/off during normal cycle? and what role does the high limit thermostat in the blower housing play?

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... is the high limit thermostat on the heater assem. what controls the heater element on/off during normal cycle?

... and what role does the high limit thermostat in the blower housing play?

1) there's (2) different Hi-Limits on the Heater Housing

2) and another different Hi-Limit on the Blower Housing

there's a Thermistor on the Blower Housing that measures the air temperature and sens info to the Main Controller

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so one of the high limits on the heater housing is the thermal fuse that is tripping out permanetly, the other should trip first and reset when cooled? and the main controller is what realy cycles the heaters with the reading from the thermistor in the blower housing?

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Definitely venting issue---as Regus has posted.

 

**********

 

<<<I will also check for no heated air when on fluff>>>
 
***********
 
This test---rules out a "shorted-to-ground" heating element (very rare on LG electric dryers)
 
***********
 
<<<also I'm a little unclear, is the high limit thermostat on the heater assem. what controls the heater element on/off during normal cycle? and what role does the high limit thermostat in the blower housing play?>>>
 
***********
 
With a normal/clear vent system---the THERMISTOR on the Blower Housing sends temperature data (of the heated exhaust air) to the Main Board. The Heater Relay on the Main Board will then correctly cycle the Heating Element on or off.
 
Like most dryers today---there's several "layers" of safety redundancy that have been designed to minimize the risk of fire should a malfunction occur.
 
If the vent system becomes blocked (even partially)---the Heater Housing will reach excessively high temperature *before* the exhaust air temperature flowing past theTHERMISTOR on the Blower Housing reaches the target temperature for normal cycling of the Heating Element.
 
Initially the HIGH LIMIT THERMOSTAT (self-resetting)---at the rear of the Heater Housing---cycled (turned off) the Heating Element.
 
When the High Limit Thermostat "closed" again---Heating Element function resumed (at this point---the Heater Housing is already exceeding normal temperature). After several cycles of turning the Heating Element "on" and "off"---the THERMAL LIMITER (mounted at the center of the Heater Housing) "opened" and shut-down the Heating Element "permanently"---until the cause of the abnormally-high heat is identified and repaired (along with a new THERMAL LIMITER).
 
The self-resetting High Limit Thermostat on the Blower Housing---performs the same function as the self-resetting High Limit on the Heater Housing---but is used for monitoring (potential) excessive air temperature of the *exhaust air* (caused by a different type of malfunction---not a restricted vent system).
With a restricted vent/slow air flow---the air temperature at the Blower Housing does not usually spike.
 
NOTE: Only LG *gas* dryers have resettable Thermal Limiters on the Heater/Burner Housing.
 

 

 

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thank you for taking time to explain.

I will follow up with all the test suggested once it's back together.

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just wanted to update

while installing the new thermal fuse I also replaced the high limit thermostat in the heater housing and the thermistor in the blower housing. even though they checked good, they were cheap to replace while I was in there.

 

doing the suggested checks, everything seem to check good

no heat while in the fluff cycle

heat turned off when door open

output temp at vent with empty load on high heat  150-170, med heat 132-155, lowest heat 105-118

ran dryer for 20 min on high heat without blowing thermal fuse.

 

plan to install dryer this weekend, and will redo vent for little or no flex, and hopefully no way they can kink it.

 

thanks regus and john for your patience and help

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