How to shut lgx25971st down to defrost - LG LFX25971ST Bottom Freezer French Door Refrigerator

Either the thermostat is prematurely shutting down the compressor or the latter is overheating and the clixon is shutting it down.

The defrost timer also will shut down the compressor and all fans but that is only once every 10 hours or so to defrost unit. In about t10 15 minutes the timer will turn the compressor back on.

Replace the defrost thermostat. They are cheap and 90% of the time will be the problem.

you will probably have to change the controler

no defrost timer runs through control most common issue is limiter

Hi welcome to fix-ya. The defrost is started when white sensor located top of coil left side. That tell the motherboard to defrost. When done the same sensor shuts down defrost. The defrost termintor that is wired in line with heater is only for safety. I hope this helps.

Hi,
Frost accumulating on the freezer is an indication of a defrost failure. It likely has one of three failures.
1 Bad defrost heater.
2 Bad defrost termination switch.
3 Failed defrost timer
In order to confirm, which has gone wrong manually advance this refrigerator into a defrost cycle. This is done by doing the following in order:
1. Disconnect power to the unit for at least 30 seconds
2. Turn the thermostat to off position (leave it off)
3. Reconnect power
In a few minutes, if you can hear a hissing noise in the freezer or see a red glow from the heater, it
indicates the timer is not advancing and will need to be replaced.
If nothing happens when the defrost timer is manually advanced, some voltage and resistance checks will need to be made. I recommend having a technician make these checks.

Hope this helps.

Shane

Hi and welcome to FixYa, I am Kelly.

The defrost cycle is usually terminated by a 60 Deg bi-metal thermostat. If the defrost heating element is not heating up the unit will shut off until the internal temp reached 60 Deg F and then restart.

Defrost cycles are 10 - 12 hours apart depending on the defrost control installed so that explains the 12 hr repeat. I really think you have a bad defrost heating element. Here is why I say that...
1. The Defrost cycle is 12 hours after last defrost. (Means the defrost control /board is working)
2. The defrost cycle terminates at 60 Deg F
3. No working defrost element will cause very very long defrost cycles due to the time it takes for the compartment to warm up to 60 deg F and terminate the defrost cycle.

The element is item 33 of this link:
http://www.appliancepartspros.com/partsearch/model.aspx?model_id=5164987&diagram_id=28252332#d28252332

Just looking at the drawing it appears that the Defrost heater and defrost thermostat are an assembly.

You should be able to read resistance end to end on the heater assembly. If you have no resistance it is most likely open / has failed.

The defrost thermostat will read resistance anytime compartment temp is BELOW 60 deg F.

Thanks for choosing FixYa.
Kelly

It is possible that the auto defrost timer is faulty and must be checked.Once the compresoor has been shut down and restarted the timer should shut down the compressor and defrost connecting the heaters.Hence check timer heater and also the thermostat(it must shut down at low setting).

Your evaporator coils frost up in normal use and every eight hours or so the entire unit shuts down and the defrost heater comes on to melt the frost. This cycle last about 20 minutes. The melted frost drips into a drain pan and through a drain tube to the drain tray under the freezer/refrigerator where it's evaporated by the condenser fan.

If the evaporator coils behind the back panel of the freezer are icing up because of auto defrost failure that will stop the circulation of cold air

check defrost timer, defrost heater, defrost thermostat. In most newer models the timer has been replaced by an electronic control board. If the heater and thermostat are ok it’ll be the control.

You can turn the defrost timer till it clicks and everything shuts down. The heater should now come on. If it does, replace the timer. If it doesn't, check the heater and defrost thermostat. Turn the timer again till everything starts back up to end the defrost cycle.

How to check everything
http://www.acmehowto.com/howto/appliance/refrigerator/refrigerator.php
If the evaporator coils behind the back panel of the freezer are icing up because of auto defrost failure that will stop the circulation of cold air and eventually affect the freezer too.

check defrost timer, defrost heater, defrost thermostat. In most newer models the timer has been replaced by an electronic control board. If the heater and thermostat are ok it’ll be the control.

You can turn the defrost timer till it clicks and everything shuts down. The heater should now come on. If it does, replace the timer. If it doesn't, check the heater and defrost thermostat. Turn the timer again till everything starts back up to end the defrost cycle.