Refrigerator not cooling

Question one: which compartment?

On a built-in with two sealed systems, this is the single most informative fact there is. Fresh food warm and freezer fine is a fresh-food-side fault: its evaporator fan, its defrost circuit, its thermistor, or a damper. Both warm together points at something shared — power, a condenser that has stopped rejecting heat, or a control. Freezer warm and fresh food fine is the rarest and usually the freezer evaporator or its defrost.

Question two: is it running at all?

Stand still and listen with the door closed. A cabinet that is silent and warm is a power, control or compressor-start fault. A cabinet that is running constantly and still warm is a heat-rejection or sealed-system problem — and those are two very different visits.

Question three: what does the coil look like?

Pull the base grille. A condenser buried under a mat of dust and pet hair explains an enormous share of cooling complaints, and it is the one cause you can remove yourself with a vacuum and a soft brush. Give it a day afterwards before judging the result — the cabinet has heat to shed before it recovers.

1. Note which compartment is warm and by how much, using a thermometer rather than the display.
2. Listen for the compressor and the fans with the door shut.
3. Pull the grille, inspect and clean the condenser, and check nothing is blocking the air path above the cabinet.
4. Check the door seals: close the door on a sheet of paper and see whether it pulls out easily, at each corner.
5. Give it twenty-four hours, then re-measure. If nothing has changed, the remaining candidates are all behind a panel.

What not to do

Do not turn the setting colder in the hope of compensating — that changes nothing about a fault and it can mask the evidence. Do not remove an interior rear panel. And do not empty the cabinet into ice chests until you have established that it is genuinely losing the battle, because a partly working refrigerator full of food holds temperature better than an empty one.