how does the auto dry feature sense humidity on my dryer

[luberhill]

OK we have a 20 year old kenmore stackable washer/dryer...we always use the setting that senses moisture to dry..its not as hot a heat as the timed heat...

Question, where. Is the sensor or whatever tells this to rotate and shut the dial off???

 And how do you know for sure it's working right

[evaappliance]

The way I check one is When the element is cycled off power should be at the timer moter  . So when you turn it on with a wet load it can take several minutes before the timer moves on the auto cycle.

[johntech]

The sensor normally is by the lint trap in the front of the drum but sometimes it is on the back wall. It is basically 2 wires that when the wet clothes hit them it closes a circuit back to the board till the clothes are dry enough that they stop closing the circuit.

[DADoESTX]

There are two types of auto-sense control systems.

Thermostatic autodry operates based on temperature.  The timer does not advance when the heating source (electric element or gas burner) is on.  The timer advances when the target operating temperature is reached and the heat source cycles off.  Premise being that the heat runs more and the timer less at beginning of a load when the clothes are more damp.  Evaporating moisture keeps the air temp lower so the heat has to run more to reach/maintain the temperature.  The heat runs less and the timer runs more as the load progresses toward dryness.  Moisture level of the load is determined indirectly.

Moisture-sensing autodry has a pair of sensor bars in the drum.  Wet clothes brushing against the bars alternately make/break a low-voltage electric circuit that either stalls the timer motor (circuit complete across the bars) or lets the timer run (no circuit across the bars).  The timer can be a mechanical dial or an electronic board.  Temperature has no bearing on this system.