Whirlpool Thin Twin dryer thermal fuse blown

Whirlpool Heavy Duty Thin Twin has worked fine for years. Then it stopped heating. I’ve checked continuity of the following parts using an ohmmeter:

3404154 fixed thermostat - closed
3399848 thermal cut off fuse - closed
3399849 thermal fuse - open

There’s a label inside the machine that tells me that a blown thermal fuse also requires the replacement of the “operating thermostat/thermistor”. But I am having trouble tracking down that part number. Any suggestions?

Also any step by step suggestions for diagnosing the original cause of the problem?

Need a model number.
Model Number Locator

If the thermal fuse is the one on the blower then I do not know why they are recommending replacing the operating thermostat.

The most common cause of this fuse blowing is a dirty or malfunctioning vent system.

The model number is YLTE5243DQ1

Cannot find DQ1 so the following is the closest Icould get DQ2
Replacement parts for WHIRLPOOL YLTE5243DQ2 WASHER/DRYER LAUNDRY SYSTEM | AppliancePartsPros.com

Here is a wiring diagram,see the attachment.
Here is your thermal fuse and the operating thermostat
AP6008376
AP6008360

Click on the picture for more info.

They recommend replacing both because they feel that the thermostat should have opened and shut off the heater before the fuse blew,
For the cost of the thermostat I would also replace it.
Note: What wires attach where as it is a 4 connector thermostat. 2 for the contacts and 2 for the internal heater so it is important that you do not get them mixed up.

Clean and check your vent system.

Also you should check the heating element.
Check the heating coil.
Unplug the unit and both wires to the coil.
Check it with a meter, should be around 13 to 20 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 fuse blows.
DQ2.pdf (369.9 KB)