The short answer
Short version: the compressor is rarely the problem. Start at frost blanketing the coil so no air moves on this cabinet and work down; the checks are ordered so that the cheapest and likeliest comes first.
What you observe
- Frost building up on the back wall of the freezer — A sheet of ice rather than the usual light dusting means air is no longer passing over the coil.
- The freezer is cold but the fresh-food side is not — Cold is being made. Something is stopping it from getting where it is needed, which narrows the list sharply.
- The cabinet is warm but the unit is clearly running — You can hear the compressor; the air inside is not cold. That combination is the whole diagnosis in one sentence.
- NEAR MISS — it cools fine but cycles loudly every few minutes — Noise with normal temperatures belongs on the noise page, not this one. Temperature is the test that decides which page you are on.
The ranking, and why it is this way round
- Frost blanketing the coil so no air moves — The coil that makes the cold sits behind the freezer rear panel, and a defrost cycle that stalls lets ice build over it week by week. Once the ice is thick enough to insulate, the fan is pushing air through a solid block and the fresh-food side warms while the freezer still looks fine. Ranked ahead of the rest since it is both the likeliest and the only one that can be settled before anything is taken apart. A value-tier build usually means simpler controls and fewer sensors, which pushes the mechanical causes above the electronic ones here.
- Dead fan: cold is made and never moved — An evaporator fan that has been chopping at ice will often stop rather than break, because the motor stalls against the obstruction. That is why this cause and the frost cause are so often found together. Second on the list — a real suspect, and the next one that can be settled by looking rather than measuring.
- A gasket that no longer seals, or a shelf keeping the door ajar — A gasket that has gone hard, torn or taken a set no longer touches the frame all the way round. Warm humid room air then flows in continuously: the cabinet cannot reach its setting and frost forms where it should not. This far down the list because it needs the two above ruled out before the evidence for it means anything.
- A leak or blockage in the sealed refrigeration circuit — It is also the only cause here where a wrong guess is expensive: condemning a sealed system that turns out to be a blocked drain or a dirty coil costs an appliance that had years left in it. Last, and the reason the order matters: it is the least likely of the four, and the three above are quicker to settle.
Check in this order, and why
- Hold your hand at the fresh-food vents with the door open and the fan running — No air movement at the vents, with a cold freezer, points straight at a blocked coil or a stopped fan. First, because it separates the top two causes in under a minute.
- Listen at the freezer with the door open and the door switch pressed in — The evaporator fan should run. Silence there, with a running compressor, is a strong result. Second, and still no tools beyond a torch.
- Look along the closed door for a light gap, and check nothing is proud of the shelves — A gap you can see at the hinge side usually means a sagging door rather than a dead gasket. Last of the owner-side checks; anything past it belongs to a technician.
The checks you can make yourself
- Empty the cabinet and leave both doors open for a full manual defrost — Cold restored afterwards confirms the defrost system as the cause rather than the mechanism.
Tools: towels, coolerAbout 90 min
- Clear debris from around the condenser fan blade through the base grille — Anything that has been pulled in from the floor can stop a blade without damaging the motor.
Tools: vacuumAbout 15 min
- Clean the gasket and the frame, then test the seal all the way round with paper — Sticky residue alone can hold a gasket off the frame by enough to matter.
Tools: cloth, mild detergentAbout 20 min
- STOP if the fault is now down to a sealed or high-voltage part — Those need tools, training and a discharge procedure. Write down what you found and hand it over.
Before you open anything
Safety
Before any panel comes off, unplug the appliance or switch off its breaker, and remember that a capacitor can hold a charge after the power is off. Wipe up spilled water before you start: standing water and a cabinet you are reaching into are a bad combination in a kitchen.
When to stop and call
Book a visit at the point where the next step is a measurement rather than a look. Call urgently if the cabinet has been above safe temperature for hours rather than minutes — at that point the food is the more expensive problem, not the appliance.
Nearest pages of this class
What this page does not cover
What you are reading is written for the class, not for one Kostch model. A family- or model-specific page, where one exists, carries what this page cannot: the exact part numbers, the board layout and the disassembly order for that line. Go there first if your model is named.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
