LG DLGX7901BE - Gas - Thermostat on back of blower keeps tripping

Dryer Repair
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1

Brand: LG
Model Number: DLGX7901BE (2 years old)
Main Symptom: Thermostat on back of blower keeps tripping
What happens & when: Thermostat trips during cycle causing dryer not to run

Error Code (if any): None
Parts or tests already tried: New thermostat 6931el3002m

The dryer powers on and i can choose a dry cycle and touch start. Timer starts counting down and the display says its drying, but the drum does not spin, and heat does not come on. Can hear the relay on the board click sending the signal for power. Found the thermostat on the back of the blower housing had no continuity. Replaced with new thermostat and it was able to do one full dry cycle before tripping the new thermostat. Dryer duct is clear all the way to outside the house. Cycling thermostat on the heater housing has continuity and trips off when hitting around 155F. Other thermostat on heater housing has continuity. I pulled the thermistor off the blower housing and measured resistance and was getting around 10.6k @ 70F. I read that its supposed to be closer to 12k. Is the thermistor the issue? Or any idea whats going on?

2

That thermistor’s reading between 70 and 80 degrees, not bad if you’re testing at room temp. 12k ohms is actually just under 70. Now, the motor 4681EL1008A could definitely be the culprit if it’s overheating. That can happen if it’s wearing out, or if there’s drag on the drum or blower making it work harder than it should. And sometimes, the motor’s internal overload protector doesn’t trip, usually because it’s fused itself closed.

3

Thanks for the reply. Upon further trouble shooting, I put everything back together and then started the dryer on a timed dry cycle using the lowest temperature setting with nothing in it. The air coming out of the outside vent read 194F in about 5 minutes and then the thermostat tripped out the dryer.. any ideas?

4

That’s way too hot for a low setting, that leans me towards the thermistor that comes with the thermostat service kit AGM30045804 is not reading correctly when it is at temperature or the main control EBR85130516 isn’t reading it properly.

5

For anyone who comes across this problem in the future, the issue was the main control board was malfunctioning. Running the installation test revealed a humidity sensor fault, but the humidity sensor tested good. Replaced the control board and dryer is running normally again