What causes a dryer to overheat?
This problem is very common and is usually attributed to roughly five different possible causes. We'll go over a list of what might be to blame for your dryer getting too hot. While a professional diagnosis is always recommend, you can easily identify some of these problems.
A lack of proper airflow in any of the ductwork or ventilation can cause overheating to occur. Make sure you keep the ventilation system clear. An annual cleaning is recommended to avoid clogging, which can both cause a dryer to overheat and pose a fire risk. Check your dryer's venting system for any obvious signs of clogging, clear it out and see if the problem goes away.
That's the most obvious, visual cause of overheating. Some issues under the surface are also possible to blame. Most notably, the heating element itself might have partially shorted which can result in continuous heat production. Regardless of what temperature is reached, the heating element simply keeps going. If this is the case, it must be replaced.
Another possible cause would be a defect with the cycling thermostat. This part is responsible for turning the heating element on or off based on the current temperature inside the dryer. It's not as likely that this part is causing your overheating issues. However, in some rare circumstances, it does happen - to troubleshoot, simply use a multimeter to check for continuity.
Two other possible culprits to check include the blower wheel and the back and front felt seal that helps retain the heat inside of the drum. Replacing the seal is easy and cheap but swapping in a new blower wheel can get a little pricey and isn't a recommended DIY dryer repair.
The blower wheel in your dryer is susceptible to damage. If it becomes faulty it could cause overheating or other issues. The most common cause of excessive wear to the blower wheel is clothing and balls of lint escaping the lint trap and falling down into the machine. Many people fail to clean their trap in time and, as a result, a significant amount of contents can fall down and get stuck in the blower wheel. Stay on top of your lint by emptying the trap before every load and never run your machine without the trap in place.