The short answer
On the Ariston ARWDF dryer line, a cycle that will not complete is worth working through in a set order: moisture sensor bars coated with softener residue first, then a drifting thermostat or thermistor, and only after those does the work that needs a meter or a teardown enter the picture. That order is written for a one-cabinet line and sequenced for how these models are put together, which is where it departs from the brand-generic article.
What you observe
- Automatic cycles stop early but a timed cycle dries fine — That split is the clearest possible evidence that the sensing is at fault, not the heating.
- Every cycle is short, and the drum never gets properly warm — Consistent shortness with poor heat points at temperature sensing rather than moisture sensing.
- NEAR MISS — there is no heat at all — That is a heating fault rather than a cycle fault, and the heating page ranks those causes properly.
Causes, most likely first on the ARWDF line
- Moisture sensor bars coated with softener residue — First on this list: an auto-dry cycle decides when to stop by measuring the resistance across two metal strips in the drum, and a film of fabric softener on those strips makes wet laundry read as dry — so the machine stops early and is convinced it has finished.
- A drifting thermostat or thermistor — A thermostat or thermistor reading wrongly cuts the heat early, which shortens every cycle equally.
- A restricted vent or lint path — A restricted vent makes the machine reach temperature without drying anything, which ends cycles early.
- Cycle selection, a timed programme or an overloaded drum — The programme and the load are worth one more look before a visit, because both are free to change.
- The control board or the timer — Last here, and the only cause on this list that is not owner work — a board or timer that advances wrongly is diagnosed with a meter on live terminals, and on a gas machine the burner control sits in the same circuit.
Check in this order, and why
- Find the metal strips inside the drum and feel them for a film — They are usually just inside the door opening on the front bulkhead. Done first because it separates the likeliest causes before any tool is needed.
- Feel the exhaust air at the outside vent during a heated cycle — Weak warmth with a clear vent puts the fault in the heating control. Second: it confirms or dismisses what the first check suggested.
- Clean the lint screen, then check the vent hose and the outside flap — Feel for strong warm air at the outside vent while the machine runs. Third, once the two checks above are clean.
Before you open anything
Safety
Unplug the appliance or switch off its breaker before removing any panel or disconnecting the vent — a capacitor can hold a charge after the power is off. Keep the whole lint path clear as routine: restricted airflow is both the cause of this fault and the reason dryers catch fire. On a gas machine, if you smell gas: do not switch anything on or off, leave the building, and call the gas utility or 911 from outside.
Models in the ARWDF family
Reference| Model number | Family key |
|---|---|
| ARWDF129(NA).1 | ariston:dryer:arwdf |
| ARWDF129S(NA).1 | ariston:dryer:arwdf |
When to call a technician
Call when the vent is clear, the sensor bars are clean, a timed cycle still fails and the exhaust is weak, because what is left is the heating control. Say which of those tests you have already run.
Nearest pages of this class
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
