Whirlpool Refrigerator Making Knocking Noise

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 refrigerator maintenance tips.

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.

When refrigerators experience temporary power outages, they may enter a safe mode. The safe mode protects the fridge's internal components from electrical overloading. You'll have to reset the power to your fridge.

• Unplug your refrigerator. If the plug is too hard to reach, switch the circuit breaker off.
• Wait 5 minutes before returning power to the fridge.
• Once power is back, open your freezer and push the light switch 3 times to trigger a cooling cycle.
• Monitor temperature over the next 24 hours.

Troubleshooting begins with finding the general source of the noise. Where is the noise the loudest: back, bottom, inside, or outside? Maybe a humming is audible everywhere. Check inside the main compartment and freezer section as well to pinpoint the noise. Also note the frequency of the sound, and if it stops when a door is opened. If opening the freezer stops the sound, this is helpful to locate.

Certain sounds are characteristic of a refrigerator and do not imply that anything is wrong. Listen to these sounds and decide whether they are common.

This is the sound of refrigerant flowing from the bottom of your appliance to the evaporator. Expect this sound with each compressor cycle.

This is water dripping onto the defrost heater in the freezer. In fridges with defrost systems, expect this sound every 10-12 hours. If your appliance doesn't have a defrost cycle, you'll want to manually defrost your freezer.

After defrosting, you may hear a popping sound.

This is ice cubes falling into the ice cube tray. When the ice maker is making ice you can expect ice every 1-1.5 hours.

This can also be the ice maker, the evaporator moving refrigerant, the evaporator fan, and the water inlet valve filling the ice cube tray with water.

This is the electronic control or automatic defrost control kicking on and off.

This is the compressor turning on and is normal up to a certain volume. In order to maintain its internal temperature, your refrigerator's compress will run on and off all of the time. When the compressor is normally running this will sound like a humming for 15-30 minutes followed by silence for 15-30 minutes, repeated over 24 hours a day. This ratio is called a duty cycle.

The compressor will run more frequently when the thermostat is set colder or when the fridge or freezer door is opened. If your compressor is running constantly or for the entirety of a 24-hour period, your compressor may be faulty.

This is characteristic of the opening water inlet valve to fill the ice maker. This is a similar sound to the dispensing of water from the front of the machine.

This sound is defrosted water dripping into the drain pan after the defrost cycle.

Forced air from the evaporator fan or condenser fan during cooling cycles is another very common noise.

At this point, you've hopefully noticed that your appliance is actually a music box! After understanding the typical operating sounds, you'll be familiar with when a sound doesn't seem right.

Certain whirring could be coming from the evaporator fan, or ice maker.

• Open the freezer compartment, and make sure the evaporator fan at the back of the compartment isn't blocked. Unblock the fan if it's surrounded by food, and see if the noise goes away.
• If the scraping sound continues, inspect your fan. Ice buildup near the blades can contribute to this sound. The fridge may be at a lower temperature from a faulty fan motor.
  • Replace your fan if it's excessively noisy.
• If the fan is not the issue, and sounds more like a creaking, inspect the ice maker. If the freezer door was left open, the ice cubes in the tray may have melted, and are unable to eject. The jammed ice maker motor is creating the noise. Follow the defrost guide to free the stuck ice.

Check for blocked air vents at the back of the fridge and objects out of place. Glass not properly situated on shelves has a tendency to vibrate.

A faulty defective defrost timer may produce a ticking similar to a clock since that's what it is. Clicking could also come from a starting relay, though this is a normal sound.

Like the evaporator, when the condenser fan is dirty, it can also cause the refrigerator to make an unusual humming or whirring sound.

If the condenser is damaged, the blade can usually be pulled off and replaced relatively cheaply. Check the grommet as well and replace it if defective.

If the fan blade is not defective, the condenser fan motor may be causing the humming noise. With time, the bearings inside the condenser fan motor can wear and tear, causing loud refrigerator noise.

Loud humming is often caused by a dirty compressor. This is different than the popcorn popping sound that the compressor makes on startup or shutoff. A failing compressor may make a single loud knocking sound as it begins to pump refrigerant, sometimes repeating the noise when it shuts off.

If you notice a distinct rattling coming from the bottom of your refrigerator, inspect for a loose drain pan. The drain pan catches water and could have vibrated loose.

The evaporator fan blows cold air around the freezer. 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. The following tips may help your freezer maintain a safe temperature:

• 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.

View the knob or dial that sets the device temperature. Verify it is set to cold and hasn't been bumped or shifted positions. Your freezer should be set at zero degrees Fahrenheit (-18 degrees Celsius). Use a thermometer if you don't have a digital thermostat display.

A fridge out of level may refuse to cooperate or cool effectively. It might also make strange noises. Level your fridge.

• Start by adjusting the front feet. Use a bubble level and correct any side-to-side wonkiness in the fridge.

Tilt the fridge back slightly. This will allow doors to close on their own, increase efficiency and prevent ice maker issues.

A buildup of interior frost and ice can affect your unit's efficiency. If it's been a year or more since you last defrosted the freezer, perform a forced defrost or manual defrost.

• Unplug or power down your unit
• Unload freezer and carefully remove ice.
• Lay towels in the bottom of the machine, and then place bowls of hot water or a hairdryer/heat gun — carefully — in a position to melt the ice.
• Completely dry freezer before powering back on.

If you have an auto-defrost unit, accumulation of thick ice suggests some part of the defrost cycle has failed.

Door seals are gaskets for your fridge, and as they age and fall apart, cool air escapes through the cracks in door seals.

• Inspect your door seals, then clean or replace if necessary.

At the backside and bottom of your fridge is the condenser and its coils. Refrigerant passes through the coils which dissipates heat during the cooling cycle. As dust and debris pile onto the coils the fridge becomes less efficient the fridge must work hard to cool down.

• Pull your fridge out and inspect coils.
  • Your fridge may have an anti-tip bracket and can only be removed by pulling straight out from the wall.
• Clean dust off condenser coils and fan with a stiff condenser coil brush and vacuum.
• Work carefully during this task and avoid bending or damaging the tubes.

The condenser fan draws air over the compressor and through the condenser coils. If the fan motor isn't working normally, then the fridge won't cool properly.

• Check the fan blade for physical obstructions. If the blades are cracked, splitting, or missing, replace the blades.
• Rotate the fan by hand. If it doesn't spin freely, replace the motor.
• If it spins freely, test the motor for continuity. Replace the condenser fan motor if the continuity test fails.

The evaporator fan draws air over the cooling coils and circulates this air within the fridge and freezer compartments. The evaporator fan should be running as long as the compressor motor is running. If your fridge only has one evaporator fan motor it's located in the freezer compartment. When the fan fails it won't circulate the cold air to the refrigerator. In this event, the freezer may still get cold while the refrigerator stays warm.

• Check the fan blade for physical obstructions. If the blades are cracked, splitting, or missing, replace the fan blades.
• Note: The fan may not be running if it's iced up due to a freezer building up ice.
• Rotate the fan by hand. If it doesn't spin freely, replace the motor.
• If it spins freely, test the motor for continuity. Replace the evaporator fan motor if the continuity test fails.
• An unusually noisy motor should be replaced as well.

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).

• Locate and remove the Thermistor.
• There's often one thermistor in the freezer, and one in the fridge.
• Grab a multimeter and continuity test the thermistor. You can measure the thermistor if it is 46 degrees Fahrenheit (7 degrees Celsius) 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.

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. These boards are often misdiagnosed. Check other components to be certain this is the cause of the problem.

• If the display LEDs or Temperature Setting button are not responding, it could signal that the board has failed.
• Remove the board from the fridge, and reconnect. Verify the wire connections are secure.
• Replace the temperature control board.

Sometimes if the refrigerator isn't cold enough, the compressor might be having difficulty starting up. The start capacitor serves as a battery to give the compressor a boost of power during startup. If the start capacitor is burned out —and smells burnt — the compressor might not be able to start and run as often as it should.

• Safely remove the capacitor and discharge with a discharge tool.
  • On smaller capacitors, you can use a screwdriver to discharge. But be careful as capacitors increase in size.
• Test the start capacitor first with a capacitance meter; they don't fail often. If it's faulty, replace it.

The overload relay is a protection device in the compressor circuit and is often combined with the start relay. You can find it plugged directly into the side of the compressor. If the fans are running and your compressor won’t start, or if you hear a clicking sound from the unit follow the troubleshooting below.

• Safely remove the start relay assembly.
• Check the overload relay for signs of overheating or arcing.
  • This may be a hot module, burnt, or rattles when shaken.
• Check for continuity with a multimeter.
  • Flip the unit over and test again. If there's no continuity, replace the unit.

The start relay is a small device mounted to the side of the compressor. It provides power to the run winding, along with the start winding, for a split second at startup to help get the compressor going. If the start relay is defective, the compressor may run intermittently or not at all, and the refrigerator will not get cold enough. The start relay should be replaced if defective.

• Safely remove the start relay assembly.
• Test Start Relay with a multimeter. View the video above and verify if your start relay is functioning.
• Replace the relay if it fails the testing or has a burnt odor. Depending on your start relay, you may have to test the start capacitor and overload relay first and use a process of elimination. If the other two components pass continuity tests, and your compressor isn't starting, try replacing your start relay.

Modern refrigerator compressor technology has shifted from single-phase DC motors to 3-phase DC-controlled AC motors.

What this means is that instead of the start relay assembly normally attached to the compressor pins — the start relay, overload relay, and overload capacitor — there is now a sealed motherboard and a lot of wires. The inverter board modulates the power supplied to the compressor and allows for more efficient operation.

This new technology is harder to test, so follow this helpful video.

The inverter board must be tested by the process of elimination.

• First, test the input voltages. The inverter board will have both a 120V AC main power supply voltage and a 4-6V DC voltage from the main control board. Remember to make all voltage measurements with everything connected.
• If one of these voltages is missing, the inverter board will not work.
  • Backtrack to find the issue. You could have a faulty wire harness connector, a bad motherboard, or another issue.
• Second, follow the compressor continuity testing from above to verify your compressor isn't shorted and is okay.
  • If the compressor is fine, and the board input voltages are fine, then your inverter board has failed and needs replacing.

The compressor — also called the condenser — is the workhorse of your fridge. By pressurizing the refrigerant, the evaporator is able to create cold air. If the compressor is very noisy when you start it up, it may have been damaged in transit, or you could just have a faulty compressor.

If the overload relay, start relay, and start capacitor pass continuity testing, then you may have a defective compressor.

• Test the compressor for continuity by following the video above.
• Resistance values vary based on the compressor.
• Values outside of the range or a short to ground will mean replacing the compressor, which is a costly repair.
• If your fridge is more than a few years old, you may be better off replacing the fridge instead of the compressor.

If there is a refrigerant leak, the fridge won't be able to maintain a proper temperature. Your compressor is likely running non-stop.

• Contact a service technician to inspect your compressor.
• This may result in refilling or replacing your refrigerant, or replacing the entire fridge.

Finally, if the refrigerator doesn't cool enough, the main control board might be defective. This is not common. Check the defrost system, cooling fans, and cooling controls first.

• If the buttons on the control board and its LEDs are no longer responsive, remove the board from the fridge, and reconnect.
• Verify the wire connections are secure.
• Replace the control board.

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