May 12


Refrigerator Knocking Noise: How To Fix It

By Robin Hatch

May 12, 2023

If your refrigerator is making a loud knocking or banging sound, the issue is likely caused by a loose compressor, blocked refrigerant flow, fan blade obstruction, or components of the defrost cycle. Tightening fittings, cleaning coils, removing obstructions, or replacing defective parts can eliminate the knocking noise.

Hearing strange knocking sounds coming from your refrigerator can be worrying. Luckily, understanding the most common causes behind refrigerators banging and knocking can help you pinpoint solutions.

This guide covers the typical reasons a refrigerator is making loud thuds, pounds, knocks or hammering noises, and how to troubleshoot and fix the problems. Read on to determine what’s causing the racket and restore peace and quiet to your kitchen.

What is that knocking sound?

Refrigerator knocking sound

Knocking coming from a refrigerator is usually due to one of these issues:

Loose Compressor

The large compressor contains a refrigerant that is compressed to cool the interior. If the compressor unit comes loose, the vibrations create a banging or pounding sound. Tightening the bolts holding the compressor mounts should stop the knocking noise.

Blocked Refrigerant Flow

Refrigerant flowing through the sealed system can make knocking noises when there is a restriction or blockage in the refrigerant circuit. Dirt buildup on critical components like the condenser coils can disrupt normal refrigerant flow. Thoroughly cleaning condenser coils and connections may resolve minor flow issues. Major blockages require professional HVAC service to diagnose and repair the sealed refrigerant system.

Defrost Cycle

On frost-free refrigerators with automatic defrost cycles, you may hear a knocking sound coming from the appliance every 8-12 hours as the unit enters defrost mode. The rapid heating and cooling of metal parts causes expansion and contraction that produces a knocking or clicking noise. However, unusually loud or frequent defrost cycle knocking likely indicates an issue with the defrost timer or heating element that requires replacement.

Fan Blade Obstruction

If any items fall behind the evaporator fan blade inside the refrigerator, they will cause a knocking, clicking, or buzzing sound as the fan spins into the obstruction. Carefully removing any debris like food packages blocking the fan blade stops the noise.

Why is my refrigerator vibrating?

Common sources of refrigerator vibration include:

  • An uneven floor causes the unit to rock and vibrate when opening or closing the doors. Leveling the refrigerator stops movement.
  • Loose internal components like the fan or compressor rattling after coming loose from brackets. Tightening all fittings with a wrench removes slack and rattling.
  • Failing motors, like the compressor motor, cause increased vibration from wear before completely breaking. Replacing aging motor components reduces vibration issues.
  • Imbalanced evaporator fan with accumulated debris or a bent blade throwing off the rotation. Cleaning or replacing the fan removes the imbalance.
  • Loose refrigerator cabinet coming away from the wall and vibrating. Pushing the unit fully back into position and re-securing to the wall prevents rattling.

What is that dripping and gurgling sound?

The sounds of dripping or gurgling coming from your refrigerator are typically due to:

  • Condensation drips from the evaporator coil into the drain tube, which runs into the drip pan under the appliance. Ensure the drain tube is draining properly into the pan.
  • Clogged defrost drain. During automatic defrost cycles, melted ice drips into the defrost drain tube. A clogged tube causes noticeable gurgling and dripping. Unclogging the tube stops the noise.
  • Refrigerant flowing through the evaporator coils makes a gurgling sound during normal operation. But loud gurgling could indicate low refrigerant levels requiring professional recharging.
  • Ice maker filling with water before freezing into ice cubes. This periodic noise during ice maker operation is normal. But consistent dripping could mean a leaky water connection.

Why is my refrigerator rattling?

Rattling noises coming from inside the refrigerator typically stem from:

Faulty Evaporator Fan

The evaporator fan circulates cold air through the fridge and freezer compartments. A failing, unbalanced, or loose fan unit will vibrate and make buzzing or rattling noises. Replacing older fan motors or tightening brackets usually fixes this.

Faulty Condenser Fan

A clicking, buzzing, or rattling condenser fan at the back/bottom of the appliance points to a damaged or unbalanced fan assembly that requires replacement to stop the noise.

Faulty Compressor

Compressors nearing the end of their lifespan often start to rattle loudly before completely failing. Replacing an aging compressor making abnormal rattling sounds can prevent full breakdown.

Key Takeaways:

  • Knocking noises commonly come from a loose compressor, refrigerant flow obstruction, defrost cycle, or debris hitting fan blades.
  • Address the source of vibration whether it’s an uneven floor, loose components, failing motors, imbalanced fans, or a loose cabinet.
  • Dripping and gurgling noises often originate from drain tubes, the evaporator coil, the ice maker, or a clogged defrost drain.
  • Rattling frequently stems from failing evaporator fans, condenser fans, or an aging compressor.
  • Diagnose the specific issue causing refrigerator noises and address it promptly before it worsens.


What causes a banging sound in my refrigerator?

A loose compressor unit or fan blade obstruction from debris are common cause of loud banging noises coming from the refrigerator interior.

Why is my fridge knocking during the defrost cycle?

Some knocking or clicking is normal during defrost cycles as components rapidly heat and cool. But loud or frequent defrost knocking likely means the timer or heater needs replacing.

How do I stop my old refrigerator from rattling?

Older refrigerators often rattle due to failing motors or compressors. Replacing aging components causing loud rattling reduces noise issues.

What is causing a vibrating sound in my refrigerator?

The main culprits behind a vibrating refrigerator are an uneven floor, loose internal components, failing motors, imbalanced fans, or a loose cabinet.

Should I be concerned about knocking noises in my fridge?

Some minimal knocking during defrosts or from the ice maker is normal, but persistent loud knocking indicates an issue needing repair before it worsens.

Robin Hatch

About the author

For over a decade, Robin has been a real estate agent, interior design specialist, and mother. Through her trials and tribulations, she wanted to create the perfect website to help you save money and make your home look beautiful.

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