If there is a buildup of frost, ice, snow, and frozen water in all its forms on the back wall, you're on the right page. If you are more specifically talking about an ice maker that won't stop making ice, follow the fixes on the ice maker problem page.
It's important to perform regular fridge maintenance before trying these fixes. Your appliance should last for at least 10-15 years before needing replacement, so keep it running well with these tips.
Occasionally, you will need to defrost your freezer. If you're needing to defrost more than once a year, then follow the fixes below.
Safety Note: Power Down the Fridge
Before removing and replacing or continuity testing electrical components, power down the fridge. This will prevent damage to the components and prevent you from being electrocuted. Still, some electrical components — like capacitors — will store their charge and should not be tampered with.
- If the fridge is pulled away from the wall, or if the power switch is easily accessible, remove the plug.
- Otherwise, find the fridge’s circuit breaker in your breaker box and turn the circuit off.
- Verify your fridge has lost power by opening the doors and seeing if the fridge lights turn on.
Safety Note: Sharp Sheet Metal
When working underneath the fridge, consider wearing gloves to avoid cuts from the sharp sheet metal. The sheet metal is the thin structural metal where components mount. While wearing gloves may make work more challenging, it’s worth protecting yourself.
Hot or Wet Contents
Ice buildup happens when warm and humid air contacts cold evaporator coils in the freezer. This moisture is frozen and quickly forms into a wall of ice. By ensuring food is at room temperature before being placed into freezer containers you will avoid releasing warm air in the freezer.
Incorrectly Loaded or Overloaded Fridge
The evaporator fan blows air cold around the freezer. And while the freezer is more efficient when it is appropriately loaded with food. Too much food or incorrectly placed food will block the vents and prevent proper temperature regulation. The refrigerator vents allow for airflow between the fridge and freezer compartments. Blocking these vents may result in many issues.
- Locate your evaporator fan and move frozen items further away.
- Unblock the vents. A rule of thumb for frost prevention is to stock enough food to fill the freezer while keeping an inch of space between the food and the walls.
Door Left Open
Enough with the hot air, already! Every time the freezer door is opened, more of the warm and humid air will enter and cause ice to form. This is inevitable, though can be minimized by reducing the time spent searching for food. You may experience this issue more during humid summers than dry winters.
Ice Dispenser Chute Won’t Close
If your fridge door has a built-in ice dispenser, inspect the chute door for a stuck ice cube or piece. If the chute door is open, warm air can slowly seep into the freezer compartment.
- Remove any blockages.
Failing Door Seals
Door seals are gaskets for your fridge, and as they age and fall apart, cool air escapes through the cracks in door seals.
Defrost System Malfunction
If the evaporator cover in your freezer is covered in ice crystals or otherwise frozen over, there's an issue with your defrost system.
Frost-free appliances regulate temperature to prevent ice build-up. Automatic and adaptive defrost systems prevent and remove ice build-up by circulating heat as needed; automatic systems typically run on a timer while adaptive systems use sensors to determine when to circulate the heat.
Defrost System Initial Troubleshooting
Most modern freezers have an auto-defrost system. This defrost system has four main parts: a defrost heater, a bi-metal thermostat, an electronic control board, and a thermistor. Let's begin troubleshooting the defrost heater system.
- Test to see if the defrost heater works by putting your freezer into forced defrost mode. On some models, this mode is entered by pushing the door sensor 5 times in 2 seconds. The controller will beep and the defrost mode will start. This mode can be exited by unplugging the fridge. If this procedure doesn't work, check the tech sheet located under or behind your fridge for your specific procedures.
- Check to see if the heater heats up.
Thermal Fuse Blown
Like a breaker tripping under a power load, your thermal fuse may trip and blow when your appliance overheats. One sign that your fuse may have blown is your evaporator freezing over.
- Continuity test your fuse and replace it if the reading is more than 1Ω
Faulty Defrost Heater
The defrost heater melts frost off evaporator fins. If the defrost heater fails, the frost stays put and the entire refrigerator eventually becomes ice.
- Locate defrost heater, and if you notice any bumps or cracks, replace it immediately.
- Continuity test the heater. A resistance value outside of an acceptable 50-120Ω will need replacing.
Faulty Defrost Timer
The defrost timer is in charge of initiating 30-minute heating cycles every 10 hours of fridge run time. If this unit fails, your fridge will be stuck in either the heating or cooling cycle.
- In units with an adaptive defrost control board, you'll have to manually enable the defrost cycle.
- Turn the thermostat off for 15 seconds, then on for 5 seconds. Repeat this two more times, then turn the thermostat off.
- Defrost cycle should be turned on. Test the temperature with a thermometer to see if your fridge is heating up.
- With a manual timer, test between terminals 1 and 4 for continuity.
- Continuity here means that the cooling cycle is operating.
- Rotate the manual dial until hearing a click. Now test between pins 1 and 2 for continuity. This means that the heating cycle is working, and there should be no continuity between pins 1 and 4.
- Replace the timer if continuity tests fail, or the fridge doesn't enter defrost mode.
Temperature Control Thermostat Failure
If the refrigerator still does not get cold enough, the temperature control thermostat (also called a bi-metal thermostat) might be faulty. The thermostat allows power to flow through to the compressor, evaporator fan, and condenser fan. If the cooling system fans and compressor are running, but the refrigerator or freezer is not cooling correctly, check for an airflow or defrost system problem.
- Continuity test the thermostat.
- Make sure it's cold from the fridge or sitting in ice water.
- Replace if its resistance value is outside of 0-1Ω.
Faulty Thermistor (Defrost Temperature Sensor)
Another problem that prevents your fridge from getting cold enough is a faulty thermistor. The thermistor is a sensor that monitors the air temperature. It is connected to the control board. If the thermistor is defective, the refrigerator does not cool (or may cool continuously).
- Grab a multimeter and continuity test the thermistor. You can measure the thermistor if it is 46 degrees Fahrenheit (7 degrees Celcius) or colder. Place the thermistor tip into a cup of ice water and cool if you're above the target temperature.
- If the value isn't between 10—15kΩ, replace your temperature sensor.
Temperature Control Board Failure
If the refrigerator is not cold enough, the temperature control board might be defective. The temperature control board provides the voltage to the fan motors and compressor. The electronic control board starts the defrost cycle and regulates how often they are triggered. If the control fails, your fridge will not be able to defrost automatically. These boards are often misdiagnosed. Check all other components to be certain this is the cause of the problem.
Faulty Evaporator Cover Assembly
In some dual evaporator style fridges, the plastic cover that covers the evaporator coils can have issues sealing. If all other components test positive in continuity and have acceptable resistance values, try replacing this part.
Fridge Isn't Watertight and Airtight
Any means for air to escape your fridge is a path for hot and humid air to enter. Consider caulking silicone to the outside of the fridge where the lines come into the unit, and spray foam the holes inside of the unit. Any foam that expands out where it isn't wanted can be trimmed with a knife once it hardens. An example of this can be seen in this Samsung Ice Maker Frost Bulletin.
Main Control Board Failure
Finally, if the refrigerator won’t get cold enough, the main control board might be defective. This is not common. Check the defrost system, cooling fans, and cooling controls first.
Tip: Splice Heating Element
A fix from the community involves splicing a 15W heating element around the top section which runs along with the defrost heater. While this video is recommended for "professional appliance technicians", a competent fixer can handle this. This repair has had a lot of success addressing and preventing ice-overs in locations with high seasonal humidity.