The short answer
On the Black Decker BUC freezer a cabinet that is not holding temperature is usually warm air getting in rather than cold not being made. BUC is a broad code rather than one design, so the sequence below holds across the model list.
What you observe
- Contents soft at the top, still solid at the bottom — A drift rather than a stop: the cabinet is making some cold but not enough, which points at load, sealing or heat rejection rather than at the compressor.
- Everything thawed and the cabinet still running — A hard stop with a healthy-sounding machine.
- Heavy frost on the walls and the contents — Warm moist air is getting in and freezing out of it.
- NEAR MISS — silent cabinet, no light, nothing running — That is supply or a start device, not a cooling fault, and it belongs on the page for a unit that will not run.
Causes, most likely first on the BUC family
- Lid or door seal, hinges and levelling — First on this family — BUC is a broad code rather than one design — and this class of cabinet stands or falls on one long gasket. A seal that has taken a set, a hinge that has dropped, or a foot standing low leaves a gap that never closes and loads the machine continuously.
- Frost build-up stealing the volume — Second and consequent on the first: thick frost insulates the walls it forms on and swallows the space the cold needs to circulate. Defrosting is both the fix and the test.
- Heat rejection: coil, clearance and where the cabinet stands — Third. A freezer in a garage or against a wall is dumping heat into air that cannot take it, which shows up as a cabinet that holds fine in winter and drifts every summer.
- Thermostat, start relay and the sealed system — Last, and the group that ends in a service call. The tell is a compressor that clicks in and out every few minutes or a coil that never becomes warm anywhere along its length.
Check in this order, and why
- Close the lid or door on a sheet of paper, all the way round — First because it is the top cause and takes a minute: paper that slides out with no drag anywhere is a gap, and a gap explains everything else here.
- Look at the frost and how thick it has become — Second: heavy even frost is confirmation of the first cause, and defrosting is the only way to see the cabinet clearly.
- Check clearance and the room the cabinet lives in — Third — a unit in an unheated space or hard against a wall repeats this fault whatever else is fixed.
- Watch a full cycle with the cabinet empty and closed — Last of the owner checks: a machine that pulls down properly when empty has cleared the whole of the top of this list.
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. Never chip frost off with a knife or a screwdriver: the evaporator behind it is thin-walled tubing and a puncture ends the appliance. The sealed system is licensed work.
Models in the BUC family
Reference| Model number | Family key |
|---|---|
| BUC1100XB | black-decker:freezer:buc |
| BUC1100XS | black-decker:freezer:buc |
| BUC1100XW | black-decker:freezer:buc |
| BUC1400XS | black-decker:freezer:buc |
| BUC1700XB | black-decker:freezer:buc |
| BUC1700XS | black-decker:freezer:buc |
| BUC1700XW | black-decker:freezer:buc |
| BUC2100JB | black-decker:freezer:buc |
| BUC2100JS | black-decker:freezer:buc |
| BUC2100JW | black-decker:freezer:buc |
| BUC2120M* | black-decker:freezer:buc |
When to call a technician
Call as soon as the compressor clicks in and out every few minutes, the coil never becomes warm, or the cabinet cannot be brought back below freezing after a full defrost and a clean coil. Call immediately if you find oil around the pipework — that means the system is open.
Other faults covered for the BUC family
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