Sensor on Neptune gas dryer

Dryer Repair
1

Sensor dry mode on our Neptune always lasted 4 minutes no matter how wet the clothes were in the dryer. After opening the dryer to clean out the dust, I noticed that the sensor bar only had 2 blue wires attached to it, both at the same end. I don’t have the schematic but I did find one here and it shows two blue wires going back to the control circuit. However, there is a “sensor ground wire” part (AP3970815) for this dryer which made me think something is missing from the dryer to make sensor dry work correctly.

I suspected that the sensor bars were supposed to have a ground and that wet clothing would short across the bars which would inform the sensor circuitry to continue drying. I checked with a multimeter to see if an internal short existed; nothing showed up.

I created a grounding wire and hooked it to the two lugs at other end and then to one of the screws holding the gas valve bracket on the bottom pan. Sensor dry times are now in the 30 to 40 minute range with no clothes in the dryer.

So my question is: should the sensor be wired to ground?

2

I put a load of wet clothes in and the dryer shut off in 4 minutes again. This makes me think that the sensor bars should not go to ground. If that is the case, then the sensor circuitry is an open loop that is closed when the bars are shorted out by the wet clothing. As the moisture content goes down, there is less of a “flow” (volts or amps?) detected by the control panel.

The bars are pretty hefty for this type of application it would seem and I can get the multimeter to budge off infinity when I press a wet cloth across them. They seem clean enough but not sure what to do next at this point.