System does not go into defrost

Possibly a stuck or closed defrost sensor. The sensor gets to freezing which closes the switch. So the unit goes into defrost cycle which switches the flow of the freon on a Heatpump. The hot gas thaws the coil and the sensor. Which opens the switch and switches it back. I'm giving this answer without knowing more about the unit. Defrost light comes on & it doesn't run at all? LG system is a split unit or window unit or what?

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It doesn't defrost

1. Defrost control board

If the defrost function is not working on your refrigerator it could be an issue with the defrost control board. This control board oversees several internal conditions and regulates the activation of the defrost cycle. A faulty board can be the primary reason your refrigeration unit is not transitioning to the defrost cycle. Over time, the buildup of ice on the evaporator coil will prevent the refrigerator and freezer from maintaining proper internal temperature. It is advisable to first check the defrost heater and the defrost thermostat for continuity prior to replacing the defrost control board.

1. Main control board

A possible cause for a refrigerator not defrosting, especially on more modern units, is the main control board. The main control board acts as a "brain" for the unit controlling the defrost cycle, compressor, and run time, and essentially acts in place of the defrost timer. The control board can be tested using an ohm meter for functionality and will need to be replaced if bad.

1. Defrost timer

If the refrigerator is not defrosting the timer could be malfunctioning. Numerous times throughout the day the defrost timer should cycle the defrost heater on as a means to melt frost buildup on the evaporator coils in the freezer. If this timer does not cycle on, then it may be faulty and require replacement.

1. Defrost heater assembly

If your refrigerator is not defrosting accurately this could be an indication that your defrost heater assembly has failed. This could cause the frost to accrue on the evaporator coils, eventually blocking the airflow resulting in the unit not cooling properly. The defrost heater assembly can be monitored for continuity using an ohm meter and will need to replaced if there is none present.

1. Defrost thermostat

Another cause of your refrigerator not defrosting is a faulty defrost thermostat. A requirement for the defrost heater to activate to melt away frost on the evaporator coils is a functional defrost thermostat. The defrost thermostat senses the temperature of the evaporator coils and initiates the thawing process by activating the defrost heater. If the thermostat is faulty, it will not sense the lowering temperature of the coils and will not turn on the heater, resulting in an advanced frost build-up. The defrost thermostat can be checked for continuity by using an ohm meter; if there is no continuity the damaged part will need to be replaced.

1. Defrost sensor with fuse

Another possible cause of a refrigerator that does not defrost properly is a defrost sensor with a fuse. If the defrost sensor fails, the fuse acts as a one-time-only fail safe for the sensor -- if the sensor does not shut off the defrost heater, the fuse will blow when the set temperature is reached. This safety precaution is to keep excessive harm from your unit by the heater and is a one-time use, resulting in the replacement of the entire defrost sensor.
Defrost drain problems

1. Clogged or freezing defrost drain

If you are experiencing defrost drain issues, it is possibly due to a clogged or freezing drain that is blocking water flow to the bottom of the freezer. This will cause the defrost water to drain and drip down to the bottom of the freezer section. To correct this issue, thaw any ice or remove debris that could be causing the clogged drain or replace the drain heater.

1. Drain heater

If you are experiencing defrost drain problems, inspect the defrost drain heater. A dislocated or burnt out drain heater will result in the drain tube freezing over. Attempt to return the part to the designated position or replace the damaged part to correct the issue. Search Over 2 1 Million Appliance Parts

dont worry about it, you probably didnt get the freezer drawer closed all the way. frost will form when it doesnt get closed properly. just make sure it is closed now and the unit will clear the frost in a few days thru normal defrosting cycles. be sure that the drawer is closing on all sides by looking at the gasket and all should be ok in the future.

test this steps and fix it, use the VOM. God bless you

1. Defrost control boardIf the defrost function is not working on your refrigerator it could be an issue with the defrost control board. This control board oversees several internal conditions and regulates the activation of the defrost cycle. A faulty board can be the primary reason your refrigeration unit is not transitioning to the defrost cycle. Over time, the buildup of ice on the evaporator coil will prevent the refrigerator and freezer from maintaining proper internal temperature. It is advisable to first check the defrost heater and the defrost thermostat for continuity prior to replacing the defrost control board.
   
2. Main control boardA possible cause for a refrigerator not defrosting, especially on more modern units, is the main control board. The main control board acts as a "brain" for the unit controlling the defrost cycle, compressor, and run time, and essentially acts in place of the defrost timer. The control board can be tested using an ohm meter for functionality and will need to be replaced if bad.
   
3. Defrost timerIf the refrigerator is not defrosting the timer could be malfunctioning. Numerous times throughout the day the defrost timer should cycle the defrost heater on as a means to melt frost buildup on the evaporator coils in the freezer. If this timer does not cycle on, then it may be faulty and require replacement.
   
4. Defrost heater assemblyIf your refrigerator is not defrosting accurately this could be an indication that your defrost heater assembly has failed. This could cause the frost to accrue on the evaporator coils, eventually blocking the airflow resulting in the unit not cooling properly. The defrost heater assembly can be monitored for continuity using an ohm meter and will need to replaced if there is none present.
   
5. Defrost thermostatAnother cause of your refrigerator not defrosting is a faulty defrost thermostat. A requirement for the defrost heater to activate to melt away frost on the evaporator coils is a functional defrost thermostat. The defrost thermostat senses the temperature of the evaporator coils and initiates the thawing process by activating the defrost heater. If the thermostat is faulty, it will not sense the lowering temperature of the coils and will not turn on the heater, resulting in an advanced frost build-up. The defrost thermostat can be checked for continuity by using an ohm meter; if there is no continuity the damaged part will need to be replaced.
   
6. Defrost sensor with fuseAnother possible cause of a refrigerator that does not defrost properly is a defrost sensor with a fuse. If the defrost sensor fails, the fuse acts as a one-time-only fail safe for the sensor -- if the sensor does not shut off the defrost heater, the fuse will blow when the set temperature is reached. This safety precaution is to keep excessive harm from your unit by the heater and is a one-time use, resulting in the replacement of the entire defrost sensor.
   

Read more: http://www.appliancepartspros.com/repair-help/refrigerator-repair-help.html#9#ixzz2aX5nUL00
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In freezing weather the heat pump efficiency drops. The freezing is normal. The equipment has a board and sensor to defrost your heat pump. Now this system can fail but freezing rain and snow get pulled into the unit get pulled into the unit coil and freeze blocking airflow. You can defrost the unit by turning it to cooling. This is what the defrost board does automatically.

Error 225 refers to the scanner lamp not lighting. Theres nothing you can do but replace the lamp with a new one.

Yes very much possible that temperature sensor( defrost thermostat) or heater coils ( defrost heater) is faulty.. If you see, too much ice frost collected there, then its defrost related issue. First try manual defrost reset procedure. The procedure is as follows: ----

First unplug the unit from main power outlet. Then empty whole unit completely. Then keep both the doors open. Wait for 24 hours. All the ice collected on the coils and in the freezer section will get melted. Clean the water from the sections. Then Connect the power cord of the unit to main power outlet after 24 hours/.Then set the temperature to normal in both fridge and freezer section. It will take near to 4 hours to get run in its proper cooling cycle. Then check, if the problem returns again. Then its defrost board problem. -------------

If it's again building up ice that means the unit is not defrosting. It's starting the cooling procedure, and then while defrosting, it's not working. The defrost assembly consists of three main parts. The defrost thermostat, the defrost heater and defrost board. Any of the one is not functioning. When thermostat sense the maximum cooling, it triggers the defrost heater to start heating and this defrosts the ice collected on the coils and the system works. Both thermostat and heater are controlled by defrost board. First the thermostat and defrost heater to be checked, if both check ok by meter and visually, then its defrost board causing the problem. You can get required parts from from online sites like: --- www.repairclinic.com or from searspartsdirect online site. --------- This should help.Thanks.Helpmech.

It sounds like you have a bad defrost board or defrost sensor.
Will the unit defrost on its own?
If you take the panel off and find the defrost board, there is two pins labeled test or speed up.
Take a screwdriver or something and touch these two pins together with the unit running in heating and hold it for about 10 to 15 seconds to see if it will go into defrost. If it does then the board is OK.
Next you need to check to see if you have a coil sensor by looking on the board at the wires you will see that the wires are labeled on the board. Two of the wires should be labeled either coil or sensor.
Some of the sensors are thermistors and some are switches.
If it is a switch then you can disconnect the two wires and put a jumper across the two terminals labeled coil or sensor and with the unit running in heating and touching the speed up pins together and holding it for a few seconds and if it goes into defrost you have a bad sensor.
If it is a thermistor you can’t do this because you need a certain ohms resistance across the terminals, it won‘t hurt anything if you do jump the two terminals, it just won‘t go into defrost.
If no sensor then you have a timed defrost you should see a jumper wire and some pins labeled 30 - 60 or 90 meaning minutes. If the jumper is on 90 then move it to 60 or 30 and see if this will help this board also has the speed up jumper. With the unit running in heating by touching the two pins together it should go into defrost, if not the defrost board is bad.
If the board checks out OK then you also could be low on refrigerant.

The unit has an automatic defrost system that defrosts the fridge automatically when frost develops or when certain conditions are met.

1. Defrosting starts when the compressor running time reaches 4 hours after a power outage or after the unit is turned on for the first time.
2. Defrosting starts each time the compressor running time reaches 7 hours.
3. Defrosting stops if the sensor temperature reaches 46.4°F(8°C) or more. If the sensor doesn’t reach 46.4°F(8°C) in
   2 hours, the defrost mode is malfunctioning.
4. Defrosting will not function if its sensor is defective or wires are cut or short circuited.

If your unit defrosts frequently even when the conditions above are not met, you have a malfunctioning sensor. You may have to ask the help of a qualified technician to disassemble and:

1. Check the connections of the sensor to the control board.
2. Inspect the wires for short or cut wire.
3. Push the reset button on the main board.
4. Replace the sensor control assembly.
   

There is typically a set of jumper pins on the defrost control board that allow the system to go into defrost after 30, 60, or 90 minutes of run time. There are also two bare pins that say "test" on them. While unit is running, approx 15 min or so in heat mode, short those two pins together for about 5 seconds, this will force the unit into defrost mode. If it still does not work, you might still have a defective board. Depending on the humidity in your area, that is how you determine the defrost interval.

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