Refrigerator not cooling: what to check and what it means

First, protect the food

Keep the doors closed while you work this out. Put an appliance thermometer in a glass of water on the middle shelf of the fresh-food side; the target is 37 to 40 degrees, and the freezer should be near zero. If the fresh-food side has been above 40 for a few hours, move perishables to a cooler with ice.

Pay attention to one detail before you do anything else: is the freezer still cold while the fridge side is warm, or are both sections warm? The answer points to different causes.

The real causes, from most to least common

Frosted-over evaporator from a defrost failure. This is the one we find most. The evaporator is the cold coil hidden behind the freezer's back panel. Several times a day a defrost heater melts the frost off it. When the defrost heater, the defrost thermostat (sometimes called a bimetal) or the defrost timer or control board fails, frost keeps building until air cannot pass through. What it looks like: the freezer is still fairly cold, the fresh-food side warms up over a few days, and you may see a white frost pattern on the freezer back wall. Unplugging the fridge for a day often brings it back temporarily, which is a strong sign this is the problem. It will come back until the failed part is replaced.

Evaporator fan motor. This fan moves air across the evaporator and into the fresh-food side. When it quits, the freezer may stay cold right at the coil, but nothing gets circulated. What it looks like: no fan sound with the freezer door switch pressed, or a squeal or chirp that changes when you open the door. Ice can also form on the blade and stop it.

Dirty coils or a failed condenser fan. The condenser fan, under the unit next to the compressor, pulls air across the coils. If the coils are matted with dust or the fan has stopped, the heat cannot leave. What it looks like: the compressor runs constantly, the floor area around the unit feels warm, and both sections slowly lose temperature.

Compressor start relay. The start relay is a small plug-in part on the side of the compressor that helps it start. When it fails, the compressor tries to start, clicks off, and tries again. What it looks like: a click from the back every few minutes, no steady hum, and both sections warming. It is a common failure and a much smaller repair than a compressor.

Temperature sensor (thermistor) or control board. Modern refrigerators read temperature through thermistors and run the fans, compressor and defrost from a main control board. A bad sensor or a board that took a power surge can leave the unit doing nothing or doing the wrong thing. What it looks like: lights on, display working, nothing running; or an error code on the display.

Damper control. Many models use a motorized damper to let freezer air into the fresh-food side. If it sticks closed, the freezer is fine and the fridge side is warm, much like a fan failure.

Sealed system problems. A refrigerant leak, a restriction or a compressor that has failed. This is the least common of the list and the most expensive. What it looks like: the compressor runs but the coils never get cold, or it will not run at all with a good relay. Sealed systems are not a homeowner job under any circumstances; refrigerant handling is regulated and needs proper recovery equipment. Never cut, puncture or loosen any tubing on the back of a refrigerator.

When to call a technician

Call us if any of these are true:

• You cleaned the coils, cleared the vents and checked the seals, and the temperature has not recovered within a day.
• You see frost on the freezer back wall, or unplugging the fridge fixed it for a while and the problem came back.
• The compressor clicks on and off without running, or never runs at all.
• You hear no evaporator fan, or a loud squeal from inside the freezer.
• The display shows an error code you cannot clear.
• The unit is under a manufacturer, extended or home warranty. Opening panels yourself can complicate a claim, so file first and see our warranty repair page.

Stop using it and unplug it if you smell burning plastic, see sparks or smoke, or get a shock from the cabinet or the doors. Do not plug it back in until it has been looked at.

The diagnosis is the part that saves you money. Many warm-fridge calls end with a fan, a relay or a defrost part, not a new refrigerator. Our technicians have over 15 years of repair experience, and if a unit is not worth fixing we will tell you that before any work starts. See our refrigerator repair service for the brands and models we work on, or request a visit. We cover homes across Fredericksburg, Spotsylvania and Stafford.