Why Does My Refrigerator Run Constantly and Never Shut Off?

The Duty Cycle Baseline: What Is Normal?

Under ordinary room temperatures (68°F to 72°F), a standard residential refrigerator operates at a **40% to 60% duty cycle**—running approximately half the time. On newer variable-speed inverter compressors, the motor may run continuously at ultra-low, whisper-quiet RPM (which is normal and energy-efficient).

However, if a standard compressor is running at full power 24/7, vibrating loudly, and the cabinet still struggles to stay cold, the machine is failing to shed heat or pump refrigerant efficiently.

1. Heat Can't Escape: Caked Condenser Coils

Your refrigerator works by extracting heat from inside the food boxes and dumping it outside through the black finned condenser coils underneath the unit.

If pet hair, lint, and dust blanket these coils, thermal transfer halts. The refrigerant enters the evaporator still lukewarm. Because the thermostat never senses 37°F, the board commands the compressor to run indefinitely. Vacuuming the coils with a long narrow brush often cuts daily runtime in half immediately.

2. Failing Evaporator Fan Motor

Inside the freezer compartment, an electric fan blows sub-zero air over the evaporator coils and pushes it into the fresh food section. When its bearings dry out, the fan RPM drops from 2,800 RPM down to 800 RPM, or stalls entirely.

Even though the evaporator coils are freezing cold, cold air never circulates into the food cavity. The control board thermistor stays warm, keeping the compressor running constantly. If you open the freezer door and hear a faint groan instead of a brisk rush of cold air, the fan motor needs replacement.

3. Partial Refrigerant Loss vs. Inefficient Compressor

If condenser coils are clean and the fan blows hard, but the fridge runs 24 hours a day and the freezer only drops to 15°F instead of 0°F, you are likely looking at a sealed-system issue:

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• Micro-leak in copper/aluminum tubing: Over years of vibration, microscopic leaks vent refrigerant gas. Less refrigerant means the compressor must pump continuously to achieve minor cooling.
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• Worn compressor suction valves: The piston inside the compressor continues to stroke, but worn reed valves allow high-pressure discharge gas to slip back into the suction side, destroying compression efficiency.
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Professional Refrigerator Diagnostics in Greater Victoria

West Coast Wrench diagnoses sealed refrigeration loops, brushless DC evaporator fans, and electronic inverter boards across Victoria, Saanich, Langford, and Sidney. We quote clear flat rates before any work begins.