Show me the defrost heater on the evaporator - Miscellaneous

Your model doesn’t have a defrost timer. It has a control board that controls defrost and many other functions of your fridge. It’s located behind metal plate on outside back of refrigerator usually just above bottom grille. Heater and defrost thermostat are located behind removable panel on inside back freezer wall. Heater will be at bottom of evaporator and thermostat will be clipped on top of evaporator

You have a defrost problem. There are only three components that make up the defrost system in a refrigerator, the defrost heater, the defrost thermostat and the defrost control board or defrost timer. The best and easiest way to check the defrost system is: Remove the evaporator cover (freezer section back wall) and check the defrost heater and defrost thermostat for continuity with an ohmmeter. Check the defrost thermostat while it's covered with frost. It needs to be below 40*F to show continuity. If both check OK for continuity, the defrost control/timer has failed and must be replaced. On your model the heater never goes out and it's common for the ADC to fail. Once you determine which part needs to be replaced, defrost the entire evaporator with a hair dryer and get all the frost out, replace the cover back over the evaporator or the unit will not cool properly. The refrigerator will work normally until you replace the part. It takes a couple weeks to build up with enough frost to start affecting the cooling again

Defrost heater is going to be very close to the evaporator inside the freezer section. Take the evaporator panel off that sometimes has the evaporator fan connected to it. There you will see a dark tube that bends back and forth with wire connections on each end. That is the defrost heater.

Melt the iced up evaporator with a hairdryer for a temp. fix. The auto defrost system isn't working. I can't find diagrams of yours but here is basically how it works.

The evaporator coil behind the cover on the back wall inside the freezer will ice up under normal conditions. Every 8 to 10 hours for around 20 minutes the defrost timer (or in most newer models the electronic adaptive defrost control) will turn the defrost heater on to melt the built up ice. There is a defrost thermostat which prevents the heater from overheating the freezer by breaking the heater circuit when the temp reaches close to 32 degrees F. The entire cooling system shuts off during the defrost cycle and starts back when the timer advances through the cycle.

If this ice is not melted it will continue to build up until the air can't flow over the coil to circulate the cold air through the freezer and into the fridge. The temperature change in the fridge is usually noticed first followed by the freezer.

If the defrost thermostat is bad, it can prevent the heater from coming on OR it won't turn the heater off when it gets too warm. It is clamped to the evaporator coil at the top to sense the temp. If it appears to be misshapen it is bad.
With an ohm meter it should show continuity when cold and none when warm.
You can also bypass(disconnect the two wires plugged into it and twist them together) the thermostat to see if the heater comes on then. If it does then you know the thermostat is bad and needs replaced.

The defrost heater is located on the evaporator. It is in a tube which is at the bottom and can also go up the sides of the evaporator. On some types you can see a burnt spot if it's bad. With an ohm meter it should show continuity from end to end when disconnected from the wiring in the freezer. You can also test the wiring for voltage when it's in the defrost mode.

If you have a defrost timer you can test it. It can be located under the fridge behind the kick panel on the front. Some are in the fridge with the controls at the top. 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 because that means the timer is not running. If it doesn't, check the heater and defrost thermostat. Turn the timer again till everything starts back up to end the defrost cycle.

If you have an adaptive defrost control instead of a timer, replace it if the heater and thermostat test good. It is located in the fridge with the controls in some models and on the back in others.

The Er DH error code indicates the temperature sensor on the evaporator coil did not reach 50 degrees within one hour.
This would indicate the control board did put the refrigerator through a defrost cycle.

This problem could be caused by a defective relay on the control board, a defective defrost heater, a broken wire to the heater, or a stopped up drain on the defrost pan causing ice to form on the evaporator coil.

Before replacing the control board, someone should remove the food from the freezer, remove the freezer drawer, and remove the evaporator cover to expose the evaporator coil, heater, and defrost sensor.
The voltage to the defrost heater should be 120 volts ac.
The defrost heater is part of the evaporator coil and is not replaceable as a separate part.

You can test the operation of the defrost system by pressing "Ultra Ice" and "colder freezer temp" for 3 seconds.
The first time you press and hold the buttons the board will test the compressor, fan, and open the damper.

All displays should be on.


The second time you press and hold the buttons the board will test the compressor, fan, and close the damper.

The third time you press and hold the buttons, the board will turn the compressor and fan off and turn the defrost heater on for around 25 minutes. This would let you know if the defrost system is working.


http://knol.google.com/k/fixing-the-er-dh-code-on-kenmore-elite-trio#

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DEFROST PROBLEM
The evaporator coil behind the cover on the back wall inside the freezer will ice up under normal conditions. Every 8 to 10 hours for around 20 minutes the defrost timer (or in most newer models the electronic adaptive defrost control) will turn the defrost heater on to melt the built up ice. There is a defrost thermostat which prevents the heater from overheating the freezer by breaking the heater circuit when the temp reaches close to 32 degrees F. The entire cooling system shuts off during the defrost cycle and starts back when the timer advances through the cycle.

If this ice is not melted it will continue to build up until the air can’t flow over the coil to circulate the cold air through the freezer and into the fridge. The temperature change in the fridge is usually noticed first followed by the freezer.

If the defrost thermostat is bad, it can prevent the heater from coming on OR it won’t turn the heater off when it gets too warm. It is clamped to the evaporator coil at the top to sense the temp. If it appears to be misshapen it is bad.
With an ohm meter it should show continuity when cold and none when warm.
You can also bypass(disconnect the two wires plugged into it and twist them together) the thermostat to see if the heater comes on then. If it does then you know the thermostat is bad and needs replaced.

The defrost heater is located on the evaporator. It is in a tube which is at the bottom and can also go up the sides of the evaporator. On some types you can see a burnt spot if it’s bad. With an ohm meter it should show continuity from end to end when disconnected from the wiring in the freezer. You can also test the wiring for voltage when it’s in the defrost mode.



you have an adaptive defrost control instead of a timer, replace it if the heater and thermostat test good.


Part 501a is your main control.

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.
The evaporator coil behind the cover on the back wall inside the freezer will ice up under normal conditions. Every 8 to 10 hours for around 20 minutes the defrost timer (or in most newer models the electronic adaptive defrost control) will turn the defrost heater on to melt the built up ice. There is a defrost thermostat which prevents the heater from overheating the freezer by breaking the heater circuit when the temp reaches close to 32 degrees F. The entire cooling system shuts off during the defrost cycle and starts back when the timer advances through the cycle.

If this ice is not melted it will continue to build up until the air can’t flow over the coil to circulate the cold air through the freezer and into the fridge. The temperature change in the fridge is usually noticed first followed by the freezer.

If the defrost thermostat is bad it can prevent the heater from coming on OR it won’t turn the heater off when it gets too warm. It is clamped to the evaporator coil at the top to sense the temp. If it appears to be misshapen it is bad.
With an ohm meter it should show continuity when cold and none when warm.
You can also bypass the thermostat to see if the heater comes on then. If it does then you know the thermostat is bad and needs replaced.

The defrost heater is located on the evaporator. It is in a tube which is at the bottom and can also go up the sides of the evaporator. On some types you can see a burnt spot if it’s bad. With an ohm meter it should show continuity from end to end when disconnected from the wiring in the freezer. You can also test the wiring for voltage when it’s in the defrost mode.

If you have a defrost timer you can test it. It can be located under the fridge behind the kick panel on the front. Some are in the fridge with the controls at the top. 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 because that means the timer is not running. If it doesn't, check the heater and defrost thermostat. Turn the timer again till everything starts back up to end the defrost cycle.

If you have an adaptive defrost control instead of a timer, replace it if the heater and thermostat test good. It is located in the fridge with the controls in some models and on the back in others.

Part 13 on this diagram is your adaptive defrost control. http://www.appliancepartspros.com/partsearch/model.aspx?model_id=47967&diagram_id=669462#d669462


The evaporator coil behind the cover on the back wall inside the freezer will ice up under normal conditions. Every 8 to 10 hours for around 20 minutes the defrost timer (or in most newer models the electronic adaptive defrost control) will turn the defrost heater on to melt the built up ice. There is a defrost thermostat which prevents the heater from overheating the freezer by breaking the heater circuit when the temp reaches close to 32 degrees F. The entire cooling system shuts off during the defrost cycle and starts back when the timer advances through the cycle.

If this ice is not melted it will continue to build up until the air can’t flow over the coil to circulate the cold air through the freezer and into the fridge. The temperature change in the fridge is usually noticed first followed by the freezer.

If the defrost thermostat is bad it can prevent the heater from coming on OR it won’t turn the heater off when it gets too warm. It is clamped to the evaporator coil at the top to sense the temp. If it appears to be misshapen it is bad.
With an ohm meter it should show continuity when cold and none when warm.
You can also bypass the thermostat to see if the heater comes on then. If it does then you know the thermostat is bad and needs replaced.

The defrost heater is located on the evaporator. It is in a tube which is at the bottom and can also go up the sides of the evaporator. On some types you can see a burnt spot if it’s bad. With an ohm meter it should show continuity from end to end when disconnected from the wiring in the freezer. You can also test the wiring for voltage when it’s in the defrost mode.


you have an adaptive defrost control instead of a timer, replace it if the heater and thermostat test good.

Hi, Unplug the refrigerator. The automatic defrost is not working properly. You will need to remove the rear panel inside the freezer section and test the defrost heater and bi-metal switch. The bi-metal switch located on the top of the evaporator coil needs to be tested while it is still cold. Check and see if the switch has continuity. If the bi-metal switch shows an open circuit, replace it. If it shows a closed circuit, test the defrost heater the same way. If both the defrost heater and the bi-metal switch are ok, the defrost timer will need changed.
You will need to defrost the evaporator coils with a hair dryer. Please let me know if this helps you at all or if I can assist you further.

Thanks
Vic

Hi, If you are having frost build up, you will need to remove the rear panel inside the freezer. Unplug the refrigerator. You will need to test the bi-metal switch that is located on top of the evaporator coil and it needs to be cold when testing it. If the bi-metal switch shows an open circuit, it will need to be replaced. If the switch shows a closed circuit, test the defrost heater the same way.
If both parts show they are ok, you will need to replace the defrost control which is located inside the fresh food section in the control panel.
If it is solid ice that you find after removing the freezer panel. the drain under the evaporator coil is plugged and will need cleaned out.
I hope this helps you. Please let me know if I can assist you further.

Vic