Overview
A refrigerator should run in cycles. The compressor cools the interior, then shuts off until more cooling is required. When the refrigerator keeps running constantly, it may indicate a heavy cooling load or a fault. Many homeowners report that the fridge is not cooling properly or that the freezer is not freezing even though the motor never stops. Others notice a constant humming noise or higher energy bills.
Signs and causes
The following symptoms often appear when the compressor runs all the time:
- Continuous humming or vibration from the rear of the appliance.
- Fresh food remains warmer than expected, while the freezer may seem acceptable or begins to thaw.
- Heavy frost on the freezer wall which eventually melts and creates puddles, similar to a water leak from the refrigerator.
- Unusual sounds or louder operation compared to normal cycles, similar to what happens when a refrigerator becomes noisy.
Main causes
- Dirty condenser coils: when dust prevents heat from escaping, the compressor keeps working with no pause.
- Door gasket leaks: if warm air enters the unit, the motor cannot reach the set temperature.
- Blocked airflow: overfilled shelves stop cold air circulation between the fridge and freezer sections.
- Defrost failure: ice covers the evaporator and air cannot pass through, causing constant operation.
- Fan malfunctions: without proper airflow, the system struggles to cool effectively.
- Faulty sensors: if the control board receives incorrect readings, the compressor never shuts off.
- Sealed system problems: a weak compressor or low refrigerant charge reduces efficiency.
DIY checks
- Measure interior temperatures with a thermometer. The fridge should be near 37°F and the freezer close to 0°F.
- Clean condenser coils thoroughly using a vacuum and soft brush.
- Test door seals with the paper method: close a sheet of paper in the door and pull. If it slides out easily, the gasket leaks.
- Look for frost on the freezer wall, a clear sign of defrost system problems.
- Make sure the refrigerator has several inches of clearance for ventilation.
If the refrigerator keeps running after these checks, professional service is recommended.
Real repair cases
Case 1: Constant running due to dirty coils
One customer called because their refrigerator had been running non stop for weeks. Temperatures were acceptable but the electricity bill increased significantly. When I inspected the unit, I found the condenser coils completely clogged with dust and pet hair. The compressor was hot to the touch and never cycled off. After a full cleaning of the coils and the condenser fan area, I monitored the system for a day. The refrigerator began cycling normally again, with off periods every 30 minutes. This case shows how something as simple as blocked coils can lead to the impression of a major breakdown.
Case 2: Freezer defrost failure
Another service call came from a family complaining that their refrigerator was constantly humming and the freezer food was starting to soften. When I opened the freezer, the back wall was covered in a thick layer of ice. The defrost heater had failed, so frost kept building on the evaporator and stopped air circulation. The compressor kept running without ever reaching temperature. I replaced the defrost heater and thermostat, then allowed a complete defrost cycle. After repair, the fridge cooled normally and the compressor began to shut off as designed. This case demonstrates how a failed defrost system mimics other cooling issues.
Case 3: Faulty door gasket and warm kitchen
In another situation, the refrigerator was placed near a large kitchen window where it received direct sunlight. The gasket on the fresh food door was also torn, letting warm air inside. As a result, the compressor was running constantly but the fridge was not cooling properly. I replaced the gasket, repositioned the refrigerator away from sunlight, and educated the customer on proper ventilation. Within hours, the compressor started cycling normally and food temperature returned to safe levels. This case highlights how environment and maintenance both affect refrigerator performance.
Care and prevention
- Clean condenser coils at least twice per year.
- Check and replace worn gaskets immediately.
- Do not block internal vents with food containers.
- Keep the refrigerator away from ovens or direct sunlight.
- Defrost manually if ice builds up and arrange professional service if it reappears quickly.
