Freezer coils are iced up so the unit does not cool

There might be a few causes

Door Seal might be defective causing the door not to shut tightly this causes air from the room to get into the freezer through the opening and as the air comes in contact with the evaporator coils, it freezes. Normally the defrost system removes the ice but if the seal is defective the coils freeze too quickly and the defrost system cant keep up

If the freezer evaporator coils ice over, the defrost thermostat might be defective. Several times a day the defrost heater turns on for a few minutes to melt away any frost that may have accumulated on the freezer evaporator coils. In order for this to work, the defrost thermostat has to sense that the coils are cold enough. If the coils are cold enough the defrost heater will turn on. If the thermostat is defective it may not be able to sense the temperature of the coils and then won't turn on the defrost heater. If the defrost heater doesn't turn on, the evaporator coils ice over and eventually no air will be able to travel through the coils to provide cooling to the freezer. The defrost thermostat can be checked for continuity. It should have continuity when it reaches the low temperature of its operating range.

If the refrigerator is not defrosting the defrost heater assembly might be burned out. Several times a day the defrost heater assembly turns on for a few minutes to melt away any frost that may have accumulated on the freezer or refrigerator evaporator coils. If it fails, frost will build up on the coils and eventually no air will be able to travel through the coils to provide cooling. The defrost heater can be checked for continuity. If it doesn't have continuity it should be replaced.
Next chance is the defrost thermostat might be defective. This signals that the coils are cold enough. If the coils are cold enough the defrost heater will turn on. If the thermostat is defective it may not be able to sense the temperature of the coils and then won't turn on the defrost heater and create the same problem you mentioned. It can be tested for continuity when it reaches the low temperature of its operating range.
You may also have a bad main control board that tells everything to work when it is supposed to such as telling the defrost heaters to activate or interpret the thermostat message that it is time to defrost.

Good luck!

hello if you had ice on the rear wall of the freezer and your unit is not cooling like it should it is because your unit has a defrost issue. This is due to either the defrost thermostat, the defrost heater, or the defrost timer or adapative control having a fault condition. You would first remove the inside rear wall panel on the inside of the freezer which would give you access to the evaporator coil. If when you removed this panel you seen any ice build up on the coil you would defrost the ice with a hair dryer. You would also first check that the evaporator fan motor was working as well this part is what blows the cold air from the freezer in the refrigerator side of the unit. You would need a multimeter in order to test the defrost thermostat and the defrost heater by performing a continuity test on each with the power and each part unplugged if either part showed no continuity you would then replace which ever one had no continuity. If you find that both do have continuity message me back and I will instruct further on how to test the defrost timer in the unit as well or the adaptive control depending on which you do have. Most of the time this issue is caused by the defrost thermostat. If you have any further questions message me back I await your reply. Thanks
Rick

Its defrost problem.You need to first try manual defrost procedure.This will completely defrost the ice.But if again after few hours or few days, same problem is noticed of coils getting iced, then its defrost problem.--------- In defrost problem, mostly fridge section section stops getting cool.It cools but not properly.----- And freezer section works properly. ------------

The 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.

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.

The defrost is not working.This happens due to the evaporator coil in the inner section of freezer is got blocked by ice .--------

Try manual defrost reset procedure: ----

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. If the same problem occurs then it's defrost problem. The defrost board and the defrost thermostat/heater is not functioning properly and it has to be checked and replaced.

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The procedure of this unit is as follows: --- The compressor starts then it cools the freezer section. When the freezer reaches its cooling level the defrost cycle starts functioning. In this cycle the fan in the freezer section starts running and the cool air in the freezer section is passed to the refrigerator section and the refrigerator section gets cold. The air from freezer to refrigerator passes from the section, in that section the damper is located. Now this problem which you mentioned. In this problem the freezer thaws, this happens if the thermostat is not functioning or the heater is not heating. Then the ice starts getting collected on the evaporator coil. The evaporator coil is at the internal section of freezer. If too much ice gets collected then this ice blocks the fan in the freezer section from functioning and this blocks the damper section with ice getting collected there. This all procedure is controlled by the defrost board of the unit.

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So first try reset procedure.If that is not helping then defrost assembly parts are to be checked and replaced.The defrost thermostat is located in the freezer section beside the evaporator coil.The defrost heater is located in the freezer section beside the evaporator coil.And the defrost control board is located in the fridge section.-------------

you can get the required parts from online sites like:---

www.repairclinic.com or from searspartsdirect online site.---------This will help.Thanks.Helpmech.

remove the rear panel inside the freezer in there will be the evaporator coil,if its covered in a layer of solid ice then defrost it with a hand held hair dryer,then with the power shut off to the unit unplug the defrost heater underneath the coil and test for continuity,if this checks good then test the defrost thermostat on the top of the evaporator coil,you will need to put this on a piece of ice or cool it to below to make the contacts touch otherwise it will show open(bad) if this shows good(closed),then check for 120 volts a.c. on this circuit when is in defrost mode

sounds like the defrost heater is open and cant defrost the evaporator and it has iced over and now cold air cant circulate in the unit,its located behind a panel located inside the freezer compartment,defrost the coil with a hair dryer or by shutting off the unit and letting it melt naturally,then check the heater for continuity,also if this heater is good,then test the defrost thermostat located near the top of the evaporator coil too

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.

It sounds as if your refrigerator has stopped automatic defrosting of the evaporator coil or has a plugged defrost drain.. Below is some information provided by: www.repairclinic.com, to help you understand what may be wrong with your unit. If it is not cooling properly, you may be able to get it cooling again, temporarily by removing all perishable items, unplugging the unit, and allowing it to stand idle wth the doors open. This will allow the ice to melt, which will allow air flow to resume normally through the unit. Allow several hours for the ice to thaw completely, then close the doors and return it to an operational status. Put water in both compartments and when satisfied with the results of temperature, i.e. frozen in freezer and cold in fresh food compartment, you can put perishables back in. This will allow normal operation for only about a week until the defective part gets replaced, then it will start warming up again.
If the drain is plugged then the diagrams should show the routing so you can clean it out.
Today, all but the smaller, apartment-sized refrigerators are self-defrosting. Self-defrosting means what it implies--though frost continues to accumulate inside the refrigerator, it melts automatically. The self-defrosting system has three functional components:

Defrost timer
Defrost heater
Defrost thermostat.
Defrost timer The timer is like a clock. It continually advances, 24 hours a day. Every 6 to 8 hours, the timer turns off the cooling system of the refrigerator and turns on the defrost heater.

Defrost heater The defrost heater is similar to the burners on an electric stove. It's located just beneath the cooling coils, which are concealed behind a panel in the freezer compartment. The heater gets hot. And, because it's close to the cooling coils, any ice or frost build-up melts.

As the frost and ice melt, the resulting water drips into a trough. The trough is connected to a tube that drains the water into a shallow pan at the bottom of the refrigerator. The water is then evaporated by a fan that blows warm air from the compressor motor over the pan and out the front of the refrigerator.

Defrost thermostat The process ends after either the amount of time specified on the timer or when the defrost thermostat near the cooling coils senses that the heat near the coils has reached a specific temperature.


Detailed parts diagram:
http://www.repairclinic.com/Refrigerator-Freezer-On-Top-Appliance-Diagram