The short answer
A freezer that runs continuously and still drifts warm has usually lost its seal or its ability to reject heat, not its refrigerant. Both of the likely causes are owner-checkable and neither needs a part. Put a thermometer in the cabinet overnight rather than trusting the display. A freezer holds food safely at zero degrees Fahrenheit or below, and knowing how far off it is changes what you check. On a SPT freezer the cause that ranks first is condenser coil blanketed in dust.
What you observe
- Heavy frost building far faster than it used to — Humid air is entering, which points at the seal.
- The compressor never stops running — The cabinet never reaches its target, whatever the cause.
- NEAR MISS — the cabinet freezes properly but leaks water — That is a drain fault and it belongs on the water-leak page.
Causes, most likely first on a SPT freezer
- Condenser coil blanketed in dust — The coil cannot reject the heat the compressor removes, so the machine runs continuously without ever getting the cabinet down. It ranks first on a SPT freezer because there is very little slack behind the panels of a compact cabinet, so anything that restricts restricts completely.
- Door or lid not sealing, or left ajar — Warm humid air enters continuously, frost builds fast, and the cabinet never recovers between door openings. Second on this platform: a cabinet opened often, or one whose lid is held up by a packet, never gets the chance to catch up.
- Thermostat or control set wrong, or drifted — A mechanical dial knocked while loading, or a control that has drifted with age, leaves the cabinet running to the wrong target entirely. Ranked here because on a mechanically controlled cabinet a knocked dial is the likeliest single explanation and it is free to check.
- Defrost stalled, evaporator iced over — On a frost-free cabinet the heater stops clearing the coil, frost builds into a sheet and airflow stops while the compressor runs on. Last, and the reason to work down the list rather than guess: it applies to frost-free cabinets, and on one it is a leading cause that builds quietly over weeks.
Check in this order, and why
- Feel the coil area for heat and look for a dust blanket — A covered coil is visible, and it is the cheapest cause to fix.
- Run a sheet of paper round the seal and check the lid or door closes on its own — A seal that does not grip paper is admitting air constantly.
- Check the dial or the set point against a thermometer reading — A dial at the wrong number explains everything at no cost.
What an owner can safely check
- Unplug the cabinet and vacuum the coil and its grille thoroughly — Twice a year in a house with pets, or in a garage or outbuilding.
Tools: vacuum, soft brushAbout 25 min
- Clean the gasket and the sealing face, re-seat any lifted section and clear anything obstructing the door — Check nothing inside is holding the lid a fraction open.
Tools: cloth, paperAbout 15 min
- Set the control to its coldest useful setting and leave it a full day before judging — Judge by a thermometer, not by the display.
Tools: thermometerAbout 15 min
- STOP HERE — the next check means a meter, a panel, or both — The ranking above tells you what to ask for; it does not make the remaining tests owner work.
Before you open anything
Safety
Unplug the cabinet or switch off its breaker before removing any interior panel — a capacitor can hold a charge after the power is off. Never cut, open or attempt to recharge a sealed refrigerant line, and get help to move a loaded chest cabinet.
When to call a technician
Call when the owner checks are clear, and immediately if you see oil at the compressor or smell burning — oil outside the tubing means the system is open. On a countertop machine, get a price before committing — the labour on a small machine is the same as on a large one, and the machine is not.
Nearest pages of this class
What this page does not cover
This is the generalized page for a SPT freezer. It does not carry anything model-specific: no part numbers, no wiring colours, no panel sequence and no torque figures, because those differ between families sold under the same badge. Where a family- or model-level page exists it is linked above, and it is the more specific answer of the two.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
