Why a Refrigerator Runs but Stops Cooling

Published September 16, 2026

A refrigerator that has stopped cooling while clearly still running is one of the most common calls we take, and one of the most misdiagnosed. People assume the compressor, which is the expensive answer, when the compressor is the least likely cause on the list.

Two observations do most of the work

Before considering any cause, note these two things. They narrow six possibilities to two or three.

Which compartment failed? A refrigerator makes cold in one place and distributes it to two compartments. If the freezer is still properly cold and only the fridge section has warmed, cold is being made normally and something is stopping it moving. That eliminates the compressor and the sealed system outright.

Is there frost on the freezer back wall? A thin even layer is normal. A thick solid sheet covering the panel means the defrost cycle has failed and ice has blocked the coil.

Cause one: evaporator fan failure

The most likely cause. This fan pushes cold air from the coil into the compartments. When it fails, the freezer often stays cold because it sits closest to the coil, while the fridge section warms because nothing is carrying cold air to it.

Open the freezer and listen. On most units the fan runs with the door open, or stops briefly and restarts. Silence, with a cold coil behind the panel, points here.

Cause two: defrost system failure

Very common, and this is where the frost observation pays off. The evaporator coil runs below freezing and collects moisture continuously. A heater melts that off on a schedule, controlled by a defrost thermostat.

When either fails, frost builds until air cannot pass the coil at all. The compressor then runs continuously, the coil is bitterly cold, and almost no cold air reaches either compartment. The failed parts are modest.

Cause three: clogged condenser coils

Common, preventable and frequently the entire fault. The condenser rejects heat from inside the appliance to the room. Packed with dust and pet hair, it cannot, so the compressor runs without achieving anything.

The symptom is distinctive: the cabinet sides or rear feel hot. Garages and kitchens with pets are the worst cases. With the unit unplugged, vacuuming the coils at the rear or behind the lower front grille sometimes restores cooling within a day at no cost.

Cause four: start relay failure

Common. The relay starts the compressor, and a failed one lets the compressor hum or click repeatedly without running properly. Usually audible as buzzing from the lower rear.

This one has a safety note attached. A relay repeatedly trying to start a seized compressor draws heavy current and can overheat, so a buzzing refrigerator that is not cooling should be switched off at the wall rather than left running overnight.

Cause five: thermistor or sensor fault

Less common, and the one that behaves backwards. The control board reads cavity temperature through a sensor and cycles cooling accordingly. A drifted sensor makes a perfectly healthy appliance behave badly, either failing to cool or overcooling until produce freezes in the fresh food section.

Nothing mechanical has failed, and the part costs a fraction of what the symptom suggests.

Cause six: sealed system or refrigerant fault

The least likely and the most expensive, which is exactly the opposite of what most people assume. A leak or restriction in the refrigerant circuit requires a technician holding EPA Section 608 certification, because handling refrigerant without it is illegal.

This is also where age decides everything. A sealed-system repair on a refrigerator past about year twelve usually costs more than half the price of a replacement, which means replacing. On a newer unit it is worth doing.

Protect the food while you wait

The appliance is the smaller problem. A refrigerator above 40 degrees Fahrenheit puts perishables at risk within roughly four hours, and that clock started when the temperature rose, not when you noticed.

Move meat, dairy, eggs and leftovers into a cooler with ice in a single pass. Decide fast rather than opening the door repeatedly, because every opening costs you whatever cold is left. If the freezer is still working, leave it shut entirely and deal with the fridge section.