The short answer for these models
Warm air inside a cabinet whose compressor is working is a distribution failure, not a production one. The three things that stop cold reaching the food — ice over the cold surface, a door that no longer grips, and a condenser with nowhere to put its heat — are all visible in a few minutes and none of them needs a tool. Where this departs from the brand-level page is the ranking. A glazed door leaks far more heat than a solid one by design, so the same fault reads as more severe on a glass-door unit and the baseline you are judging against has to change with it, so on a BUC unit the door and glazing checks lead.
What you observe
- The BUC form you own, which changes what the rest of this list means — Check the door material. Glass changes the baseline: longer runs, some sweating and a warm shelf by the door are normal there.
- The cabinet is warm but you can hear it running — The hum is steady and the air inside is no colder than the room after several hours.
- Frost has built into a sheet rather than a dusting — Frost thick enough to hold a fingerprint has stopped being condensation and started being the obstruction.
Causes, most likely first on this family
- The thermostat, the sensor or the control — It sits below the mechanical causes because it is rarer, and because the checks above will have ruled most of it out by elimination. It is placed first on the BUC models rather than where the brand-level page puts it, because the form of the unit decides how much this can explain — which makes the door and glazing checks the checks with the most to say.
- The sealed system or the compressor — Bottom of the list on purpose: it is the rarest of the five, the most expensive, and the only one that is not an owner check at any stage.
What to check first, and why that order
- First — shut the door on a strip of paper and pull — The paper test costs nothing and settles the cheapest cause before you move anything heavy. On these models this is the step the construction changes: read the result against the form you identified first, because the same finding means different things on the two.
- Second — feel the condenser and the air around it — Reach behind or underneath. Dust you can lift off in a mat, or a cabinet jammed against the wall, is the cause and also the fix.
Before you open anything
Safety
Unplug the appliance or switch off its breaker before removing any panel. A capacitor can hold a charge after the power is off. Nothing sharp and nothing hot goes near an evaporator: the tubing behind the ice is thin aluminium and a puncture ends the appliance rather than delaying it. The refrigerant circuit is sealed, pressurised and worked on under licence, so leave it entirely alone.
Where the owner job ends
The line is the panel and the refrigerant circuit. Everything in front of them is yours; everything behind them needs a technician. Book the visit once the cheap causes are excluded, and book it immediately if the compressor is running hot enough to smell or the cabinet has not dropped a degree in a day.
The other symptoms covered for this family
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
