So the air flow out the back of the dryer is strong, no vent restrictions?
Does it keep tripping on HIGH HEAT?
Try MEDIUM HEAT and see if trips. I had this same problem and replaced 3 of these thermostats, all blow on HIGH HEAT, I told the customer to use MEDIUM HEAT and it hasn't blown since, that was 8 months ago.
Jake, thank you for taking the time to reply. I have no vent restrictions.
Not sure about if the dryer only trips the high thermostat when temp is high. Will try running the dryer on medium heat and see if the thermostat trips.
Do you think it may be a faulty thermistor? Why does this dryer have TWO high limit thermostats (the one that keeps tripping is the one near the flame sensor, which has a reset button)? Could it be the blower housing thermostat?
Most American made dryers have a thermal fuse, a cut-off thermostat, a high limit thermostat and a cycling thermostat. LG is a South Korean made Dryer so they may name them different and consider the cut-off thermostat another high limit thermostat, that's why there's two on yours.
Ohm test the thermistor, make sure the dryer is unplugged when ohm testing.
At 70 degrees the resistance should be 9.3K ohms, 90 degrees would be 7.7K ohms. at 100 degrees wpi;d be 6.2K ohms, 120 degrees 4.3K ohms. If the thermistor reads outside of range then it needs replaced.
If your thermistor ohm tests good, If your meter has a temperature function (a meat thermometer will work) attach the thermocouple to the vent with the vent hose off and start a timed dry, high heat cycle. The drum must be empty and the lint filter clean. Target temperature is around 150*F. The first few rises can go as high as 190* - 200*F. After that the element should shut off at around 175*F and turn on around 140*F.
My thermistor resistance measures 11.7 kilo-ohms at room temperature. I ended up replacing the thermostat with the push button reset. All the other thermostats had continuity. The flame sensor and ignitor both checked out ok. I also cleaned the burner tube.