The basic cycle: water, freezing, and ejection
Your ice maker works by filling a mold with water, freezing it solid, then pushing the ice cubes out into a bin. The whole cycle repeats automatically every few hours. A small electric motor, a heating element, and a timer control the process—no human intervention needed once you turn the feature on.
The cycle starts when a fill valve (a solenoid valve connected to your water line) opens for a few seconds and lets cold water into the mold. Once the mold is full, the valve closes. The water then sits in the freezer compartment, where the cold air freezes it solid over the next six to twelve hours, depending on your freezer temperature and how much ice you already have.
When the ice is frozen hard, a heating element wrapped around the bottom of the mold warms it just enough to loosen the cubes—not melt them, just break the bond between the ice and the mold walls. At the same time, a motor-driven ejector arm (a plastic blade or set of fingers) rotates and pushes the cubes out into the bin below. Then the cycle begins again.
Key Takeaways
- A fill valve opens to let water into the mold, then closes once it is full, and the freezer compartment freezes the water solid.
- A heating element warms the mold bottom slightly to loosen the ice cubes without melting them, and an ejector arm pushes them into the bin.
- A thermostat in the ice bin senses when the bin is full and signals the fill valve to stop, preventing overflow.
- If your ice maker stops working, the problem is usually a frozen fill tube, a clogged water filter, or a stuck ejector arm.
- Most ice makers need a water line run to the back of the refrigerator and a small drain line to remove meltwater.
The fill valve and water supply line
The fill valve is an electrically controlled solenoid valve mounted on the back wall of your refrigerator, behind the crisper drawers. It connects to the cold water line that runs into your home (usually under the sink or from a basement supply). When the ice maker's timer signals it is time to fill, the solenoid energizes and the valve opens for about six to ten seconds, allowing water to flow through a small tube into the mold.
The water line itself is typically a thin plastic or copper tube, about one-quarter inch in diameter. It runs from your home's water supply, through the wall or under the floor, and into the back of the refrigerator. If this line freezes—which can happen if the refrigerator is in a very cold garage or if the water inside the tube sits too long without flowing—the ice maker will not fill. A clogged water filter (many refrigerators have one built in) can also block the flow.
Once the mold is full, the valve closes and stays closed until the next cycle. The amount of water that enters is controlled by how long the solenoid stays open, which the manufacturer has set based on the mold size. If your ice cubes are too small or too large, the fill time may be adjustable—check your refrigerator's manual for the location of the adjustment screw.
Freezing and the thermostat that triggers ejection
After the mold fills, the water straightforward sits in the freezer compartment and freezes. Your freezer is typically set to 0°F or below, so the water hardens in four to twelve hours depending on how cold it is and how much ice is already in the bin. The colder your freezer, the faster the ice freezes.
Once the ice is solid, a thermostat inside the mold detects the temperature drop. When the ice reaches a certain hardness (usually around 15°F), the thermostat closes an electrical circuit that triggers the heating element and the ejector motor. This thermostat is a straightforward mechanical switch—it does not measure temperature digitally, but rather responds to the physical change in the mold as the water freezes.
The heating element is a thin wire or ribbon that wraps around the bottom of the mold. It draws power for only a few seconds and warms the mold just enough to create a thin layer of water between the ice and the mold walls. This layer acts as a lubricant, allowing the ice to slide out easily when the ejector arm pushes it.
The ejector arm and the full-bin shutoff
The ejector arm is a plastic blade or set of fingers attached to a small electric motor. When the heating element finishes its job, the motor spins and the arm rotates through the mold, pushing each cube out into the bin below. The arm then resets to its starting position, ready for the next cycle. This whole process takes only a few seconds.
As ice cubes pile up in the bin, they eventually reach a shutoff arm—a mechanical lever that sits near the top of the bin. When the ice level rises high enough to push this lever up, it breaks the electrical circuit to the fill valve. The ice maker stops filling and ejecting until you remove some ice and the lever drops back down. This prevents the bin from overflowing and the ice maker from running endlessly.
The shutoff arm is purely mechanical and requires no power. It is one of the most reliable parts of the ice maker because it has no electronics to fail. If your ice maker keeps running even when the bin is full, the shutoff arm is likely stuck or bent and may need adjustment or replacement.
Water drainage and meltwater management
As the heating element warms the mold to eject the ice, a small amount of water melts. This meltwater, along with any water that drips from the ice cubes as they fall into the bin, needs somewhere to go. Most refrigerators have a drain line that runs from the mold or the bin down to a drain pan underneath the refrigerator, where the water evaporates or drains into your home's plumbing.
If this drain line becomes clogged—usually by mineral deposits or ice buildup—water backs up into the mold or the bin. You may notice water pooling in the bottom of the ice bin or the ice maker refusing to eject cubes. Clearing the drain line usually solves the problem. Some refrigerators allow you to flush the line with warm water from the inside; others require you to access it from underneath or behind the unit.
The drain pan itself sits under the refrigerator and collects water from both the ice maker and the defrost cycle (when frost on the cooling coils melts). If the pan is cracked or missing, water leaks onto your floor. Checking the pan once or twice a year and cleaning it out prevents odors and mold.
Common reasons an ice maker stops working
The most frequent culprit is a frozen fill tube. If the water line or the tube leading from the valve to the mold freezes, no water enters the mold and no ice forms. This happens most often in very cold garages or if the refrigerator is set to an extremely low temperature. Thawing the tube with warm water (not a heat gun, which can damage plastic) usually restores function.
A clogged water filter is the second most common issue. If your refrigerator has a built-in filter cartridge (usually located in the back wall or inside the fridge), a dirty filter restricts water flow to the fill valve. Replacing the filter cartridge every six months prevents this problem. A faulty fill valve that no longer opens when signaled is the third common failure. If the valve is stuck or the solenoid has burned out, water will not enter the mold. This usually requires professional replacement.
An ejector arm that is stuck or broken prevents ice from being pushed out, even if the mold fills and freezes correctly. You may see ice piling up inside the mold but not falling into the bin. A broken shutoff arm can cause the ice maker to run continuously or not at all. Finally, a faulty thermostat in the mold may not signal the heating element and ejector motor to set up, leaving ice frozen in place.
When to call a professional
If you have checked that the water line is not frozen, replaced the water filter, and confirmed that the shutoff arm moves freely, but the ice maker still does not work, the problem is likely inside the refrigerator's mechanical or electrical system. At that point, a service technician can test the fill valve, thermostat, and motor with a multimeter and replace whichever part has failed.
Repair costs vary widely depending on which part fails and whether your refrigerator is still under warranty. A water filter costs $20 to $60 and you can replace it yourself. A fill valve or motor replacement typically runs $200 to $400 in labor and parts. If your ice maker is more than ten years old and fails, it may be worth comparing the repair cost to the cost of a new refrigerator.
Frequently Asked Questions
Why is my ice maker making ice but the cubes are small or hollow?
Small or hollow cubes usually mean the mold is not filling completely. Check that the water line is not kinked or frozen, and that the water filter is not clogged. If the fill valve is opening for too short a time, you may be able to adjust it—consult your refrigerator's manual for the adjustment screw location. Hollow cubes can also form if the freezer temperature is too high; try lowering it to 0°F or below.
Can I turn off the ice maker without turning off the whole refrigerator?
Yes. Most ice makers have an on/off switch or lever on the unit itself, usually located on the side or front of the mold assembly. You can also shut off the water supply valve behind the refrigerator (typically under the sink or in the basement) to stop the ice maker from filling without affecting cooling. If you are going on vacation, turning off the ice maker prevents stale ice from sitting in the bin.
What should I do if water is leaking from under my refrigerator?
First, check the drain pan underneath the refrigerator to see if it is cracked, clogged, or missing. If the pan is intact, the leak may be coming from the ice maker's drain line. Inspect the line for cracks or kinks, and make sure it is not clogged with ice or mineral deposits. If the drain line is clear and the pan is in place, the leak may be from the defrost cycle, which is a separate system. A service technician can pinpoint the source.
Do I need to clean my ice maker?
The ice maker itself does not require regular cleaning because it only handles water and ice. However, the ice bin should be emptied and wiped down every few months to prevent odors and mold. If you notice a bad smell coming from the ice, the bin or drain line may have bacteria or mold growing in it. Wash the bin with warm soapy water and flush the drain line with warm water to clear it.
Why does my ice maker make noise?
A grinding or buzzing sound usually comes from the ejector motor as it pushes ice out of the mold. This is normal. A loud crack or pop is the sound of ice freezing and expanding in the mold, also normal. A continuous buzzing or humming that does not stop may indicate the fill valve is stuck open or the motor is running without ejecting ice. If the noise is new or very loud, have a technician inspect the unit.