The short answer
A Black+Decker BUC freezer that is running and still losing temperature has usually lost either its seal or its airflow, and on this family the seal comes first: a lid or door that no longer pulls itself shut admits warm air every hour of the day. A freezer holds food safely at 0 °F (−18 °C) or below, so deal with the food while you work through the checks below. Settle the build before the ranking applies: these models divide on a drain plug low on one wall.
What you observe on these models
- Ice cream soft, packets pliable — Check the deepest food too — it tells you how long this has been happening.
- Heavy frost on the walls or the evaporator — Frost is an insulator: past a certain thickness the cabinet cannot pull heat through it.
- The compressor no longer stops — Continuous running with a warm cabinet is the pairing that matters.
- The lid or door does not pull itself shut — Frost at one corner of the opening marks the leak for you.
- Condensation on the lid or the cabinet sides — Common where the unit lives in an unheated space.
- NEAR MISS — the cabinet is silent and warming — Silence is a power, control or start-relay reading and belongs on a different page.
Causes, ranked for the BUC build
- The lid or door seal, the latch or the way the cabinet is loaded — It leads on chest builds above anything else: a basket or a packet proud of the rim holds the lid a few millimetres open and nothing about the machine looks wrong. It is the cheapest cause here and the one most often missed.
- The defrost cycle has stalled on a frost-free build — It sits second: the check is next along the same path, so nothing is wasted testing it here.
- Frost has built up far enough to insulate the evaporator — It drops to mid-list where a fan and a defrost cycle do the work, because there the frost is a symptom rather than a cause.
- The condenser coil is blanketed, or the cabinet has no air around it — It sits mid-list indoors, where it is still worth ruling out because it costs nothing.
- A start-relay, compressor or sealed-system fault — Last of the five, and that is the value of the ordering: everything above it is cheaper, likelier, and checkable without a tool.
The order that finds it fastest
- Check the seal and the closing action all the way round — It should drag at every point tried; where it slides out freely, warm air is getting in there too.
- Look for anything holding the opening apart — On a chest freezer a packet proud of the rim is enough to cost the whole cabinet its temperature.
- Judge the frost thickness on the walls or coil — A manual-defrost build past its due date will not hold temperature no matter what else is right.
- Check clearance and the condenser coil — Dust, a wall too close or a hot corner all show up as a machine that runs and does not win.
Before you open anything
Safety
Power off at the plug or the breaker before opening anything; a capacitor can hold a charge after the power is off. Do not defeat the lid or door switch to watch a fan run.
Where the owner job ends
The condition is whether anything is left that can be changed without opening the cabinet. Seals, loading, defrosting and clearance are all owner work; a defrost heater, a thermostat, a start relay or anything holding refrigerant is not. A unit that trips its breaker or smells hot should be switched off and booked the same day.
Other faults covered for the BUC models
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
