The short answer
A dryer that stops early and a dryer that runs forever are usually the same fault seen from two sides: the machine cannot tell how dry the load is, or it cannot get rid of the heat it is making. Airflow sits behind both. Run a timed cycle rather than an automatic one. If a timed cycle dries the load properly, the heat is fine and the fault is in sensing; if a timed cycle also fails, the fault is airflow or heat. On a Smeg dryer the cause that ranks first is vent restricted, so the machine cycles on its thermal limits.
What you observe
- The cabinet and the load are very hot at the end — Heat is being made and not removed, which is airflow.
- The cycle ends in a few minutes with the load still wet — Classic sensing fault: the machine believes the load is dry.
- The cycle runs far longer than it used to and the clothes are still damp — Classic airflow fault: heat is going in but moisture is not coming out.
- NEAR MISS — the machine will not begin at all — That is a start fault, not a cycle fault.
Causes, most likely first on a Smeg dryer
- Vent restricted, so the machine cycles on its thermal limits — Lint packs the duct, the machine overheats, and the safety thermostat cuts the heat repeatedly — a cycle that runs and runs while the clothes stay damp. It ranks first on a Smeg dryer because a built-in installation breathes through a narrow cabinet cut-out, so anything airflow-related surfaces here long before it would on a free-standing machine.
- Drum overloaded, so the load never tumbles — A packed drum rolls as one mass, never passes the sensor and never lets air through, so the machine either times out or cuts out hot. Second on this platform: it is free to rule out and it is the cause that a compact drum reaches soonest.
- Moisture sensor bars filmed over with softener residue — Two metal strips inside the drum read the load's resistance, and a film of dryer-sheet residue insulates them so the machine reads every load as dry. Last, and the reason to work down the list rather than guess: it produces a short cycle on a wet load, which is the single clearest signature in this list.
Check in this order, and why
- Feel the exhaust at the outside vent while the machine runs — Weak or cool airflow outside settles it before anything is opened.
- Dry half the load and see whether the cycle behaves — If half a load completes normally, the machine is fine.
- Look for two metal strips just inside the drum opening and feel for a waxy film — A dull, slightly tacky strip is the answer.
What an owner can safely check
- Disconnect the duct at the back and run the machine for a minute on air only — Strong airflow at the machine and weak airflow outside means the duct is the fault.
Tools: torch, screwdriverAbout 25 min
- Split the load in two and run one half on the same programme — A drum should be no more than about half full for air to move.
About 5 min
- STOP at the point where the next check means live terminals or a panel removed — Everything past that line is a technician's work, however likely the cause above it looks.
Before you open anything
Safety
Unplug the dryer or switch off its breaker before opening any panel, and treat a machine that is overheating as a fire risk until the duct is proven clear.
When to call a technician
Call once airflow and sensing are both ruled out, and stop using the machine immediately if you smell scorching or the cabinet is too hot to touch. On a European-controlled machine, ask what the control was reporting when it stopped — it usually records why it aborted, and that shortens the visit.
Nearest pages of this class
What this page does not cover
What this page covers is the dryer class as Smeg builds it, not an individual family or model line. If a page exists for your particular family or model, it is linked above and it is the better answer — go there first when your model is named. Left out on purpose: part numbers, connector colours, disassembly order and torque values, because every one of those varies by family.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
