An Asko dryer moisture sensor is the part of the control system that lets an automatic program decide when laundry is dry. Instead of simply running for a fixed time, the dryer checks how much moisture is left in the load or in the air leaving the drum, and it ends the program when that reading says the load has reached the dryness you chose. How the reading is taken on your exact model, and which programs use it, is described in the owner’s manual; the principle below is how automatic drying works in general.
What does a dryer moisture sensor actually do?
Wet fabric conducts electricity and dry fabric does not, and wet laundry also puts more water into the air passing through the drum. Dryers use one or both of those facts to estimate how dry a load is. Some dryers use small metal contacts in the drum that touch the tumbling clothes; others watch the condition of the air leaving the drum. Either way, the control board compares what it reads to the target for the program you selected and ends the program when the load reaches it.
Which method your Asko uses, and how many levels of dryness it offers, depends on the model. Treat any claim about the exact mechanism on a given machine as something to check in the owner’s manual.
It helps to think of the sensor as an estimate rather than a measurement. It does not weigh the water in the laundry; it reads a signal that usually goes with dryness, and the control board turns that signal into a decision. That is why a clean, free-flowing dryer with a sensible load gives accurate results, while a dryer working against a blocked filter or a film on the sensing surface gives results that look random.
How is an automatic program different from a timed program?
A timed program runs for the time you set, whatever state the clothes are in. It is useful for a single damp item or a refresh, but it can leave a heavy load wet or over-dry a light one. An automatic program keeps drying until the sensor decides the load is ready, which is why its length changes from one load to the next. A towel load and a shirt load will not take the same time even on the same program.
This is also why the length of a cycle should be read against your own baseline rather than a number from anywhere else. Our article on Asko dryer cycle duration explains why automatic programs vary in length.
What fools a moisture sensor?
The most common cause is a film. Fabric softener, dryer sheets and detergent residue can leave a thin layer on whatever surface the sensor reads, and a coated surface reads wetter or drier than the laundry really is. The second cause is airflow: a lint filter that is full, a condenser that is clogged, or a room that is very humid changes how fast the load dries, so the sensor keeps the program running longer than the load needs.
Load size matters too. A very small load can pass between readings and end early, and an overloaded drum cannot tumble freely, so the middle of the pile stays damp while the sensor reads the surface. Mixing heavy items such as towels with light synthetics in one load produces uneven results, because the light items dry first and the heavy ones are still wet when the program ends.
How do you keep an automatic program accurate?
Start with airflow, which is the owner job that matters most. Clean the lint filter after every load, not every few loads, and look after the condenser or heat pump filters as your manual describes. Our guides on the lint filter routine and condenser filter cleaning cover the habit.
Next, keep the sensing surfaces clean. If you can see bare metal strips inside the drum, wipe them with a damp cloth while the dryer is cool and switched off, and let them dry. Use less fabric softener, and avoid dryer sheets if they leave a film. Sort loads by weight, fill the drum loosely, and choose a dryness level that matches the fabric. These habits solve most sensor complaints without any part being replaced.
Keep a simple record for a couple of weeks if the results seem odd. Note the program, the load type and whether the clothes came out damp, dry or over-dry. A pattern, such as only towels coming out damp or only small loads ending early, usually points straight at the cause, and it gives a technician a far better starting point if a visit is needed.
When does a dryness problem point to a fault?
If the filters and condenser are clean, the load is sensible and clothes still come out damp or the program ends far too early, the sensor, the wiring or the control board may be at fault. That diagnosis needs a technician: the cabinet must stay closed, because the dryer holds live electrical parts and, on heat pump models, a sealed refrigerant system. For the symptom side of the question, our page on a dryer with clothes still damp lists the checks in order.
If you notice a burning smell, scorched fabric or smoke, stop the dryer and switch off the breaker at the panel while standing on a dry floor. Do not run it again until it has been inspected. Our Asko dryer repair page explains how a visit works.
