Ok, so the first go around of overheating that lead to the Dryer shutting off I tested and then replaced the thermal fuse and not the thermostat. That lasted all of 15-20 minutes of run time.
So next I replaced the thermostat, the blown thermal fuse, removed the front off of the dryer cleaned the lint trap area, and the squirrel cage fan that draws air out of the dryer. I reconnected the dryer vent to the back of the dryer and kept the end that would normally go into the wall up where I could ensure airflow. I started the dryer and felt good airflow coming out of the vent. about 15 minutes later the dryer shut itself off again. Touching the back of the dryer near where the heating element is located it felt very hot.
Any ideas what could be causing it to overheat and blow the thermal fuses?
Check the heating coil.
Unplug the unit and both wires to the coil.
Check it with a meter, should be around 10 to 12 ohms.
Then check from each side of the coil to the case/frame, both should be infinite ohms (open). If not the coil may have sagged or broken and is touching the case. This can cause it to run on high and the thermostats cannot regulate it so the thermal cut-off blows.
The hi-limit should have regulated the temperature so the fuse did not blow, that is why there is a new one with the thermal cut-off…
Note: That unless there is another problem in the unit the hi-limit should never have to open. It is just a safety device with the fuse being a backup safety device.
Just in case it is not a grounded element.
With all the below the high limit will also have to be replaced which you have done so just check the below.
Check that the belt is OK.
Check the seals (drum etc) in the unit. The air is pulled over the heating coils, through the drum and pushed out the exhaust. So any large seal leak will pull in room air and the cycling thermostat on the blower will run the unit hot.
Check that the lint filter is not coated with fabric softener residue which greatly reduces air flow.
Check/clean your vent system.
Check/clean the blower wheel.
If all OK you may want to replace the cycling thermostat as it’s contacts may not be opening (welded shut)
