My Samsung moisture sensor dryer turns on but just hums and won't start drying then turns off what could be wrong?

Question edited for spelling 'Lent' to 'Lint'.

The auto dry feature uses a humidistat to sense the amount of moisture in the air as it is exiting the dryer.

The thermistor / thermostat is a heat sensing device and that is the one to change first. If inaccurate it cuts the heat off to soon resulting in a warm heat drying cycle instead of HOT.

There are two other devices, a thermal fuse which will cut power when the dryer over heats and it doesn't sound like yours is. Finally there is a Thermal Cut Out, and when it overheats so badly the fuse breaks and has to be renewed.

The other thing to check is the the vent outside is clear of lint and that the flap or grille vents are opening fully when the dryer is running..

Good videos, and the second video shows testing components.

Your dryer has a moisture sensor that determines how long the drying cycle is on. When the dryer is first started it has an initial run time based on the selected setting. When the sensor starts measuring the moisture the drying time will change to a shorter run time if the items are not too wet. It could also be that the sensor needs to be cleaned. Dryer softener sheets can coat the sensor over time and prevent the sensor from accurately reading the moisture. You can use s scrub pad such as a scotch-brite to gently clean the sensor. https://www.samsung.com/us/support/owners/product/gas-dryer-with-steam-dv501ag

If it's in the timed cycle, the timer motor is probably bad, preventing the timer from advancing through the cycle.

If it's in the auto dry cycle, the moisture sensor could be bad, so the dryer thinks the load is still wet.

replace the wet dry sensor by ythe lent trap

Yes that is your moisture sensor bar.

Try cleaning off the moisture sensor bars. (two 1/4 inch wide, about 5 inch long metal strips about an inch apart inside the dryer, near the lint trap.) These strips can get coated, often times from waxy residue from fabric softener sheets, and then no moisture is detected, so the dryer thinks clothes are dry, and after a short (5 minutes) cool down, it shuts off. If you use the manual / time dry, dryer should work fine even if the sensors are coated.

I think the vent is pluged up or bent so that the lent is trapped in the hose. its getting too hot. don't use it anymore till you get it cleaned and check for lent build up in side. can cause fire.

F03 MEAN SENSOR DEFAULTPUMP OR LENT

try timed dry cycle instead of the auto-sensing setting. In your drum if you have auto dry such as less dry normal dry and more dry, There is a sensor sometimes in the drum and sometimes in the exhaust right after the blower. If in the drum then your clothes brush by this and if moisture is sensed then it keeps on drying. With your rack the clothes can't touch the sensor so it tells your dial to turn and that items are dry which in fact are not. Try this and see how it does.

This may be a problem with your moisture sensor or the control that read the sensor. If it is under warranty have Samsung fix it for free. Make sure the cycle settings are correct before tinkering. First make sure the electronics are not too dusty. You could blow them off or vacuum them. Dirt particles can conduct electricity and make it read wrong. Next check the electrical connection for the moisture sensor. See if its location is in the manual. If it doesn't work after some tinkering asked the service for the dryer about possibly replacing the sensor but first try hard to get it to work.