Is your freezer is filled with Ice due to refrigerator heater not working ?, Here is how to fix it .
Almost every refrigerator have a heating element behind the freezer compartment. Usually , It’s located in the evaporator assembly. Touching the aluminum fins of the evaporator. Sometimes , malfunctioning heater or it’s components can cause greater problems. Here is how to troubleshoot , test and fix your refrigerator heater.
Why Refrigerator needs a Heater
You might ask why a Refrigerator needs a heater. After all , cooling is the main purpose of a refrigerator. Right ? .As we have mentioned in our [ previous article ] . During the cooling circle of a refrigerator the ice will build up in the evaporator. Thus , causing lot of problems . As an example, Ice can cause stuck fan blades. Also , Ice build up can increase the temperature inside the refrigerator (due to evaporator being covered by ice) . So , Refrigerators need some component to melt this ice periodically. That’s where the heater element comes to play. It melt the ice within 10 – 15 minutes .
The Causes of Heater not working
If you need to find the causes of refrigerator heater not working . You need to look in to the wiring diagram of your refrigerator. Usually ,It’s in the back plate of your refrigerator. If not , You need to find the user manual or the service manual of your refrigerator.
You need to check every component that connected to the heater power rail. Here are some of the components that may affect the function of the heater.
This is the first component you need to check . This is same as the water heater you use in your house hold. Except , longer and high resistant. Thus , lower heating power. Because , You don’t need to melt the plastic parts inside the freezer and cause fire. These heating elements have power rating between 150Watts to 250Watts . Available in both 110v and 230v ratings .
How Heater Element works – Inside this tubing a spring shaped Nichrome (NiCr) wire covered with a dielectric powder such as , Magnesium . Supply voltage is being applied between the to ends of the Nichrome coil . The current flow causes the Nichrome coil to get heated. Since , It has a higher melting point (1400 °C) it doesn’t melt during the defrost circle .The dielectric powder also a good heat conducting material will also get hot due to conduction. Thus , Heating the outer tubing .
How to Check The Refrigerator Heater
There are two methods to check a heating element of a refrigerator .
Using a Multi-meter – Put the multi-meter in Ohm scale and touch each heater connector pin with each multi-meter probes. If you are getting a reading between 150 Ohm to 300 Ohm you may have a good heating element . If you are getting OL (Over load) reading or higher resistance value , You may have a bad heating element.
Also touch the outer tubing with one probe and the other probe on any pin of the connector . you should get a OL (Over load) reading or higher resistance value . If you are getting a low scale reading you may have a bad and unsafe heating element .
Caution ! – The next step Involves high voltages use safety measure. If you don’t have any previous experience with high voltage . please , get help from someone who has that experience.
By powering it up – If you doesn’t have a multi-meter .The only way to check it is by powering it up .
Powering up using Defrost timer (Recommend) – Locate the defrost timer . Assuming your timer is in cooling mode . Use a plier or screw driver to turn the defrost timer rod very slowly. Until , you hear a clicking sound . Stop turning as soon as you hear that sound . Because , If not it will go back to cooling mode . Since, there is very tiny time frame for defrost circle, The rod only have very little movement in defrost circle (< 5°). The timer rod only can be rotated at a one direction .So , Be careful not to turn in wrong direction . Now you are in defrost mode. Power up the refrigerator (Make sure the Thermostat and heater is plugged correctly ) and check whether the heater is heating up by putting your hand close to it .
Powering up using Direct wires – Not going to explain due to safety issues involved .
Bad Defrost Timer
This is one of the main causes of refrigerator heater not working. As we mention in our [ previous article ] the defrost timer have two states , One for cooling circle the other is for defrost circle. The heater only powered through the timer relay on defrost mode. So , If the defrost timer not working there is no power to the heater .
Bad Thermal Fuse
The thermal fuse inside the freezer is a safety device designed to prevent overheating of the heater element of the refrigerator. This fuse will blow at a set temperature (~72°C) . Cutting the power to the heater .
[ Here is how to check the Thermal Fuse of a refrigerator ]
Bad wiring can cause power interruptions in the refrigerator. The wiring can go bad due to several reasons. Such as , rats can damage the wiring and the aged wires can get hard and brittle .
Fix – Firstly , Inspect the wiring with you eyes. If you find an damaged wires replace or solder the wires together. But , Sometimes the damage is no visible to naked eyes. Put your multi-meter in continuity mode and put the probes between start and end of a wire. Then , check each wire connection using long wire probes while inspecting the wiring diagram.
Oxidized Connector Pins
If you are living in a coastal area , You know how bad the corrosion is . The copper pins inside the connectors of your refrigerator is very venerable to corrosion and oxidization. Which creates layers of oxides in top of the copper pins breaking the connection between pins. Thus , creating open circuits. The level of oxidization depends on the weather conditions .More humid conditions can cause more oxidization .
Fix – Unplug and Clean each connector pins using a tooth brush soaked in Isopropyl Alcohol or spray contact cleaner and brush the pins with tooth brush. Then , plug them back together.
Frequently Asked Questions
Can I replace the Heater element with a different one ?
Yes you can . But , Certain criteria must be met . The shape and the size of the heating element should be same or near match . If not , it will not fit to the evaporator assembly . The electrical ratings (Voltage and current ratings ) should match to the old heater elements ratings . However , You don’t have to match the connector type .Becuause , You can use the old heater’s connector and connect it to the new ones wires . Make sure to properly insulate the wires .
Heater barely Heats , Do I need to replace it ?
Although , Refrigerator heater doesn’t heat that much . You must feel the heat as you close your hand to the heating element . If you barely feel the heat , You may have a bad heating element or a bad heater wires . You must replace it . There also one unlikely reason , Bad / Burned defrost timer contacts can also cause not heating elements .
Can I replace only the Thermal Fuse ?
Thermal fuse is inside a sealed package to avoid any current leak and there is a gas inside this sealed package prevent any oxidization of the thermal switch .If you cut the package to replace the thermal fuse , The gas inside it will leak . Even if you sealed it back, The air inside the package can cause oxidization. That’s why you need to replace the whole package instead of repairing it.
Disclaimer – The contents of this article may change anytime.This tutorial involves working with high voltages . In order to work with such voltages , It requires special tools and protective equipment. Make sure to take every safety measure necessary . If you don’t have any experience working with high voltages .Please , Get someones (Someone who have experience ) help to follow this tutorial.If you are not a experienced technician , Don’t work on the refrigerator while it is connected to the mains.Depending on the measuring equipment you are using readings may vary . Please , Use good quality measuring equipment to take the readings.