A blown thermal cutoff thermostat could be the cause why your Whirlpool 29 inch electric dryer is not heating at all.
This thermostat is a safety device used to blow and open the heating element circuit if the temperature inside of the heater box excides or get hotter that the temperature rated on this device.
It is located on the top outside of the heater box and it's job is to monitor the temperature inside of the heater box.
There are few ways that the temperature inside of the heater box could rise. The first one is if the exhaust hose gets restricted. For example, I seen cases where the people goes on a 2 weeks vacation and when they come back, birds have made a nest inside of the exhaust hose restricting the air flow though the dryer. The complaint is that the dryer is not drying the clothes.
The other problem it is cause by a grounded heating element. Grounded heating element means that the heating element gets welded to the metal casing and stays on even when the thermostat has cycle off.
Before replacing this thermostat, you need to make sure that the airflow coming from the inside of the dryer is strong. If you just replace the thermal cutoff and don't correct the airflow, the thermostat will blow again in a short time.
To replace it do the following. Disconnect the dryer from the wall outlet. Remove the back panel to get access to the thermostats.
Find the heating element and on the top left side of the heating element housing you will see the fuse. It ism called a fuse because when it blows you need to replace it with a new one. This is the part number 279769 and you should replace the 2 pieces in this kit.
Watch the video below to see how this repair is done.
Below are the links to the parts needed for this repair.