Refrigerator Making Humming Noise but Not Cooling: Troubleshooting Guide
Quick answer
A humming refrigerator that isn't cooling may have dirty condenser coils, a faulty thermostat, or a compressor issue. Clean coils, check the thermostat setting, and ensure the fridge is level.
Confirm the symptom
- Refrigerator is making a continuous humming sound
- Interior temperature is not cooling properly
- Freezer compartment is also not freezing
- No clicking sound when the compressor should start
- Condenser coils are warm but not hot
Tools and prep
- Screwdriver set — For removing panels and accessing internal components
- Infrared thermometer — To check temperature of condenser coils and evaporator
- Multimeter — To test electrical components like thermostat and compressor
- Soft brush — To clean dust from condenser coils
- Level — To check if refrigerator is level
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Prep & safety
- Unplug the refrigerator to avoid electrical hazards before inspecting internal components.
- Allow the refrigerator to rest for at least 30 minutes to let the system depressurize.
Step-by-step troubleshooting
Check Condenser Coils
Do: Locate and clean the condenser coils using a soft brush or vacuum.
Observe: Coils are dirty or clogged with dust.
Means: Dirty coils reduce heat transfer efficiency.
Next: Clean the coils thoroughly and wait 24 hours to see if cooling improves.
Verify Thermostat Setting
Do: Check the thermostat setting to ensure it is not set to 'off' or too high.
Observe: Thermostat is set to an incorrect temperature.
Means: Improper settings prevent the compressor from running.
Next: Adjust the thermostat to the recommended temperature (35-38°F for refrigerator, 0°F for freezer) and monitor performance.
Inspect Compressor
Do: Listen for the compressor to engage and feel for vibrations.
Observe: Compressor is humming but not starting.
Means: Compressor may be failing or have a start relay issue.
Next: Test the compressor with a multimeter to check for continuity and voltage.
Check Refrigerator Level
Do: Use a level to ensure the refrigerator is sitting evenly on the floor.
Observe: Refrigerator is tilted or uneven.
Means: An unlevel fridge can prevent the door from sealing properly.
Next: Adjust the leveling feet to stabilize the refrigerator and test the door seal.
Test Door Seal
Do: Inspect the door gasket for cracks, gaps, or debris.
Observe: Door seal is damaged or not sealing tightly.
Means: Poor seal allows cold air to escape.
Next: Clean or replace the door seal as needed and test cooling performance.
Check for Frost Buildup
Do: Look for excessive frost or ice in the freezer compartment.
Observe: Frost buildup is present on the walls or coils.
Means: Defrost system may be malfunctioning.
Next: If frost is excessive, unplug the refrigerator and allow it to defrost completely before testing again.
Inspect Start Relay
Do: Locate the start relay and test it with a multimeter.
Observe: Start relay shows no continuity or is burned out.
Means: Faulty start relay prevents the compressor from starting.
Next: Replace the start relay with a compatible model and test the refrigerator.
Check for Electrical Issues
Do: Inspect the power cord and outlet for damage or loose connections.
Observe: Power cord is damaged or outlet is not providing power.
Means: Electrical issues can prevent proper operation.
Next: Replace the power cord or use a different outlet and test the refrigerator.
Common causes table
| Cause | Why | Likelihood | Difficulty | Part often needed |
|---|---|---|---|---|
| Dirty condenser coils | Reduced heat transfer efficiency | High | Low | Condenser coil brush |
| Faulty thermostat | Incorrect temperature settings prevent compressor activation | Medium | Low | Thermostat |
| Compressor failure | Compressor not starting or running properly | Medium | High | Compressor or start relay |
| Poor door seal | Cold air escaping due to damaged gasket | High | Low | Door gasket |
| Frost buildup in freezer | Defrost system malfunction | Medium | Medium | Defrost heater or thermostat |
| Refrigerator not level | Improper leveling affects door seal and compressor performance | Low | Low | Leveling feet |
| Electrical issues | Damaged power cord or outlet | Low | Low | Power cord |
Parts matching
When replacing parts, ensure compatibility with your refrigerator model. Check the model number on the appliance and match the following specifications:
- Condenser coil brush: model number and coil size
- Thermostat: voltage and compatibility with refrigerator model
- Door gasket: refrigerator model and door size
- Start relay: voltage and amperage rating
- Defrost heater: wattage and length
Purchase parts from the manufacturer or a reputable appliance parts supplier to ensure compatibility.
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When to call a pro
- If the compressor shows no signs of starting despite testing
- If the refrigerator is under warranty and you don't want to risk voiding it
- If you are unsure about electrical testing or component replacement
- If the issue persists after replacing all suspected parts
- If refrigerant levels are suspected to be low (requires licensed HVAC technician)
FAQ
Why is my refrigerator humming but not cooling?
A humming sound with no cooling can indicate dirty coils, a faulty thermostat, or a compressor issue. Start by cleaning the coils and checking the thermostat setting.
Can a dirty condenser coil cause a refrigerator to stop cooling?
Yes, dirty condenser coils reduce heat transfer efficiency, which can cause the refrigerator to stop cooling properly. Clean the coils regularly to maintain performance.
How do I know if the compressor is faulty?
If the refrigerator is humming but the compressor is not starting, it may be faulty. Use a multimeter to test for continuity and voltage.
What should I do if the door seal is damaged?
Inspect the door gasket for cracks or gaps. Clean or replace the seal as needed to ensure a tight closure and prevent cold air from escaping.
Can an unlevel refrigerator affect cooling performance?
Yes, an unlevel refrigerator can prevent the door from sealing properly, leading to cold air loss. Adjust the leveling feet to stabilize the appliance.