Fridge not cooling but the light is on? 7 likely causes

You open the door, the light comes on, and the milk is lukewarm. It is a frustrating moment, because it feels as if the fridge is working. The light, however, runs on a completely separate circuit from the cooling system. All it proves is that the fridge has power. The part that actually makes things cold is a sealed system made up of a compressor, two coils, a fan or two, a thermostat and a defrost system, and any one of them can fail while the light carries on shining.

Here are the seven causes we find most often on Durban fridges, in roughly the order we would check them.

1. The compressor is not starting

Stand next to the fridge in a quiet room. A healthy fridge hums for a while, goes quiet, then hums again. If you hear nothing at all, or a click every few minutes followed by silence, the compressor is not running. Very often the cause is a worn start relay or overload protector, which are small and inexpensive parts. Sometimes the compressor itself has failed. Either way this needs a technician to confirm.

2. The condenser coil is clogged with dust

The coil at the back or underneath the fridge is where heat leaves the system. When it is covered in dust and pet hair, the heat cannot escape, the compressor overheats and the cabinet stops cooling properly. In Durban's humidity that dust turns into a sticky film that is harder to clear than it looks. Switch the fridge off, vacuum the coil gently and check that there are a few centimetres of space around the unit.

3. The evaporator fan has stopped

On frost-free fridges, a small fan inside the freezer pushes cold air into the fridge section. If that fan fails, the freezer can stay quite cold while the fridge warms up, because the cold air has nowhere to go. You may hear a rattle or a squeal before it stops, or hear nothing at all where there used to be a soft whoosh.

4. The evaporator is frozen over

If you can see a thick layer of frost on the back wall of the freezer, the defrost system has probably failed. The ice blocks the airflow, so the fridge gets little or no cold air. You can clear it temporarily by switching the fridge off and letting it thaw for several hours, but it will return until the faulty defrost heater, timer or sensor is replaced.

5. The thermostat or control board is faulty

The thermostat tells the compressor when to run. If it fails, the compressor may never get the signal to start, or it may stop too early. Before you suspect the part, check that nobody has knocked the dial or the display to a warmer setting. It happens more often than you would think.

6. The door seal is leaking

A perished or dirty door gasket lets warm, humid air in all the time. The fridge then runs constantly and still cannot catch up. Close the door on a sheet of paper. If it slides out easily anywhere around the door, the seal is not doing its job.

7. The refrigerant has leaked out

A fridge is a sealed system, so it never needs topping up in the ordinary course of life. If the gas is low, there is a leak somewhere, and adding more without fixing it only delays the problem. This is also not a job for do-it-yourself kits. Many modern fridges use a flammable refrigerant, and the work needs proper equipment and training.

What you can safely check yourself

• Confirm the fridge dial or display has not been changed.
• Listen for the compressor running and feel whether the back is warm or cold.
• Clear the vents inside the fridge and freezer so air can move.
• Look at the back wall of the freezer for a layer of ice.
• Test the door seal with a sheet of paper.
• Vacuum the condenser coil with the fridge switched off at the wall.

What not to do

Do not keep switching the fridge on and off to see if it will come back, because repeated start attempts can damage a compressor that is only struggling. Do not pierce or tamper with any pipes. And do not leave food in a fridge that is above 5 degrees for more than a couple of hours. Move it to a cooler with ice packs while you wait.

When to call a technician

If the compressor is silent, if there is ice on the back wall, if the fan is not turning or if you have tried the checks above with no change, it is time to call. Tell us the make and model, whether the freezer is still cold, and what you can hear. That helps us arrive with the right parts. We repair household and commercial fridges across Durban and the surrounding areas, and we will give you an honest view on whether the repair makes sense.