Most refrigerator faults trace back to airflow, not to a dying compressor. Dirty condenser coils, a stopped fan, a blocked defrost drain and a tired door seal cause the large majority of problems people assume are terminal. All four are checkable in under half an hour, and none of them require opening the sealed refrigerant system.
How a refrigerator actually works
Knowing the loop makes almost every fault easier to place, because each symptom maps onto a specific stage.
- The compressor pressurises refrigerant
This is the hum you hear. It pushes hot, high-pressure gas out to the condenser.
- The condenser dumps heat outside the cabinet
Those are the coils on the back or underneath. If they are blanketed in dust, heat cannot escape and nothing inside gets properly cold — no matter how hard the compressor works.
- The refrigerant expands and gets cold
It passes through a restriction into the evaporator, the coil hidden behind the back panel of the freezer.
- A fan blows air over the evaporator
In most modern fridge-freezers, all the cold is made at this one coil and then blown where it is needed — including into the fridge compartment through a duct.
- A defrost cycle melts the frost off
Several times a day a heater briefly warms the evaporator so frost does not build up. The meltwater runs down a drain hole into a pan on top of the compressor, where it evaporates.
Two consequences worth holding on to. First, if the freezer is cold but the fridge is warm, the cold is being made and not delivered — that is a fan, duct or damper problem, not a compressor problem. Second, if you find water inside the fridge, the defrost drain is the first thing to suspect.
Find your fault by symptom
| Symptom | Most likely cause | Full guide |
|---|---|---|
| Nothing is cold anywhere | Dirty condenser coils or a failed fan | Refrigerator not cooling |
| Freezer cold, fridge warm | Evaporator fan, blocked vent or stuck damper | Freezer cold but fridge warm |
| Food freezing in the fridge | Setting too low, damper stuck open, or items in front of the vent | Refrigerator freezing food |
| Water inside or under the fridge | Blocked defrost drain | Refrigerator leaking water |
| No ice being made | Frozen fill tube, supply off, or filter overdue | Ice maker not working |
| Thick frost on the freezer back wall | Defrost system failure or a poor door seal | See the four checks below |
| Running constantly and never resting | Coils, seals, or a door not closing | See the four checks below |
| Buzzing, clicking or rattling | Fan, compressor relay, or something touching the cabinet | See the noise section |
The four checks that solve most faults
Condenser and evaporator fans start without warning whenever the compressor cycles, and the blades will take a fingertip. Unplug the refrigerator at the wall before cleaning coils or removing any internal panel.
- Clean the condenser coils
Back panel on older machines, underneath behind a kick plate on most modern ones. Vacuum them and brush the dust out with a coil brush. In a home with pets this single job restores cooling more often than any other. Do it twice a year as routine.
- Check both fans actually run
The condenser fan sits by the compressor at the back; it should run whenever the compressor does. The evaporator fan is behind the freezer back panel; press the freezer door switch and listen for it. A silent fan with a hot compressor is a strong lead.
- Test the door seals
Close the door on a sheet of paper and pull. If it slides out freely, the seal has lost its grip at that point. Do this at several points around each door. A poor seal lets warm, humid air in, which causes frost build-up, constant running and condensation all at once.
- Clear the vents inside
Find the air vents between freezer and fridge and make sure no packet, box or bag is pressed against them. Blocking the outlet starves the fridge of cold air; blocking the return stops the circuit working at all.
After any of these fixes, a warm and fully loaded refrigerator takes many hours to pull back down to temperature. Do not conclude the repair failed until a full day has passed.
What the temperatures should be
| Compartment | Target | Notes |
|---|---|---|
| Fridge | 3–5°C (37–40°F) | Below 3°C and salad items and milk start to freeze at the back |
| Freezer | −18°C (0°F) | Ice makers generally need this to cycle at all |
| Ambient room | Above 10°C (50°F) | Fridges in unheated garages often misbehave in winter |
Use a standalone fridge thermometer rather than trusting the display. Put it in a glass of water in the middle of the fridge and read it after several hours — that gives you the true food temperature rather than the air temperature at the moment the door opens.
What the noise is telling you
| Noise | Likely source |
|---|---|
| Steady hum | Normal — the compressor running |
| Gurgling or trickling | Normal — refrigerant moving, or defrost water draining |
| Popping or creaking | Normal — plastic liners expanding and contracting |
| Loud buzzing or vibration | Cabinet touching a wall, or a fan blade fouling ice or debris |
| Rapid clicking every few minutes | Compressor start relay failing to start the compressor |
| Rattling from underneath | Loose drip pan or condenser fan blade |
| Squealing from the freezer | Evaporator fan motor bearing wearing out |
Repair or replace?
Cheap and worth doing at almost any age: door seals, thermostats and thermistors, defrost heaters and timers, evaporator and condenser fans, drain clearing, ice maker modules.
Expensive and worth thinking hard about: compressors and anything inside the sealed refrigerant circuit. On an appliance past roughly ten years, a sealed-system repair usually costs enough that replacement makes more sense — and a modern unit will use meaningfully less electricity, which shifts the sums further.
A refrigerator does not consume refrigerant. If a technician says it is low, there is a leak, and simply recharging it means paying again when it empties. Ask where the leak is and what repairing it costs before agreeing to anything.
When to call a professional
Call an engineer if the coils are clean, both fans run, the seals are sound and the vents are clear but the refrigerator still will not hold temperature. That points at the sealed system — a refrigerant leak or a failed compressor — and that work is restricted to technicians with refrigerant handling certification in most countries. Also call for any burning smell, scorched wiring, or a unit that trips the breaker.
Stop and call a qualified appliance technician or electrician if you find scorched or melted wiring, smell burning, see water that has reached electrical components, or if the fault returns immediately after a repair. Never bypass a safety device — thermal fuses, door interlocks and flood switches fail for a reason, and defeating one converts a broken appliance into a fire or flood risk.
