The compressor is the loudest single part of a fridge. Some hum is normal. Harsh or changing sounds point to a problem you can diagnose quickly.
Compressor basics
A fixed-speed compressor cycles on and off. Starts are the loudest moments. Inverter and linear compressors vary speed, so they hum more steadily and quietly. Less starting and stopping means fewer noise spikes.
Normal sounds include a low hum during operation and a brief click at start or stop. Gurgles and hisses from refrigerant are also common. Noises that are continuous, metallic, or tied to poor cooling need attention.
Quick identification
If the noise comes from the back bottom, you’re near the compressor and condenser section. Put a finger lightly on the cabinet back. Strong vibration there often means a mounting or fan issue. If the noise stops when you open the freezer door, that is the evaporator fan, not the compressor. For a full system flow, start with our Refrigerator noise troubleshooting guide and the Refrigerator fan noise repair guide.
Describe the sound. A loud steady hum that heats the rear panel suggests overload or poor airflow. A repeating click every few minutes with weak cooling points to a start relay or compressor that cannot start. Grinding or knocking often indicates internal wear.
Safe first steps
Open a 1-2 inch rear gap and 0.5-1 inch on the sides. Clean the condenser coils and grill. Level the cabinet left to right and raise the front slightly so doors self close. Keep the cabinet from touching walls or counters. Add dense rubber pads under feet on hard floors. These steps lower load and vibration and often reduce compressor noise without tools.
What each sound usually means
| Sound | Likely cause | First action |
|---|---|---|
| Low steady hum | Normal running | Monitor |
| Louder hum with hot rear | Poor airflow or heavy load | Clean coils, open clearance |
| Repeating click, no cooling | Start relay or compressor won’t start | Check/replace start relay; call pro if persists |
| Buzzing at start then stop | Locked or overheating compressor | Unplug, call a pro |
| Knocking or grinding | Internal compressor damage | Call a pro |
| Rattle near base | Loose pan, mounts, or lines | Tighten, pad, secure |
Mounts, fans, and lines that make compressors seem loud
A noisy fridge is not always the compressor itself. Worn rubber grommets under the compressor let vibration pass into the frame. Replace cracked or flattened mounts with OEM parts. A loose drain pan can buzz at certain speeds. Pad it with thin foam tape and reseat it. A condenser fan with debris or wobble will rattle and amplify hum. Clean and tighten before judging the compressor.
Keep water lines from touching the cabinet. Secure them with clips. A thump during fills is water hammer, not the compressor.
Inverter and linear compressors and noise
Variable-speed designs cut loud starts. Samsung’s digital inverter compressors adjust speed in steps and run more smoothly. LG’s linear compressors hold a steady hum and vary speed to match demand. Real-world noise depends on cabinet insulation, fan control, and install quality, but variable-speed designs are generally quieter than fixed-speed.
DIY vs pro: where to draw the line
You can handle airflow, leveling, gaskets, drain pans, fans, and mounts. Do not open the sealed refrigeration circuit. Handling refrigerant requires training and specialized tools. Intentional release is illegal. If a compressor will not start after a new relay, runs hot and loud, or makes grinding or knocking sounds, bring in an EPA-certified technician.
Decision guide: repair or replace
Age, cost, and noise goals drive the choice. Most refrigerators last about 10-15 years. If an older unit needs a compressor or sealed-system repair, costs often approach replacement.
Typical repair cost ranges (US)
| Item | Parts + labor range |
|---|---|
| Compressor replacement | $350 – $650+ (higher for built-ins) |
| Condenser or evaporator fan motor | $100 – $300 |
| Start relay | $80 – $200 |
| Door switch | $50 – $150 |
Simple decision grid
| Age | Repair cost | Cooling performance | Recommendation |
|---|---|---|---|
| < 5 years | <$250 | Good | Repair |
| 5-8 years | $250-$400 | Good | Repair or monitor |
| 8-12 years | $300-$600 | Fair | Lean replace |
| 12+ years | Any major repair | Any | Replace |
If quiet operation matters for sleep or open-plan homes, look for inverter or linear compressors and variable-speed fans, plus solid insulation and published sound ratings. Many shoppers search for a quiet compressor refrigerator; variable-speed designs are your best bet. For model picks, see our quietest refrigerators buying guide.
How to tell if the compressor is bad
Normal refrigerator compressor noise is a steady hum. A refrigerator compressor loud enough to hear across rooms, or a compressor making noise that includes grinding or knocking, is not normal. Repeating clicks with no cooling point to a start relay or a seized compressor. If the cabinet at the back gets hot and the hum stops and restarts, the compressor may be overheating.
Simple checks: clean condenser coils, open rear airflow, and relevel the appliance. If a new start relay does not help and the compressor still will not run, call a technician.
FAQs about refrigerator compressor noise
Is refrigerator compressor noise normal
Yes, a low hum and a brief click at start or stop are normal. Louder hum, knocking, or repeated clicking are warning signs.
Why is my refrigerator compressor making a loud humming noise
Dusty coils, poor clearance, or an unlevel cabinet can make the compressor work harder and sound louder. Clean coils, open airflow, and add dense pads under the feet to reduce the noise you hear.
What is the compressor replacement cost
Compressor replacement cost typically ranges from $350 to $650+ for parts and labor, and can be higher on built-in models. Compare this to the age and condition of the appliance before committing.
Safety
Unplug before you work. Avoid the sealed system. If you smell burning, hear harsh metal sounds, or the compressor is too hot to touch, stop and call a pro.