Why Dryer Is Overheating? 7 Common Reasons

Clothes dryers are obviously designed to heat up so that you can dry your clothes faster, but what happens when they get too hot?

There is more than one reason why this might be happening, from the heating element to the thermostat.

One of the most common causes of an overheating dryer is poor airflow. However, other potential reasons could be a problem with the heating element, thermistor, blower wheel, or one of the many thermostats in your clothes dryer.

Restricted Airflow

What is it: Air needs to be drawn into the clothes dryer through ventilation on the outside of the unit’s housing.

This air is warmed by a heating element, which then draws the moisture out of your clothing via a blower wheel.

Clogged dryer vent outlet

Why it fails: Oftentimes, the exhaust in the back of the clothes dryer or outside the vent line gets clogged with accumulated lint.

Conversely, the flexible exhaust may become kinked. Both can lead to your unit overheating.

How to fix: Using a screwdriver (typically Phillips), unscrew the coupling that holds the exhaust hose in place.

Then, use a long wire brush or equivalent to push out any blockage that may have built up inside.

Additionally, you should check your lint trap, as well. Removing any buildup will reduce the chances of your dryer getting too hot.

Failed Heating Element

What is it: The dryer’s heating element is responsible for heating the air that is drawn in before it enters the unit’s drum. This is simply coiled wire affixed inside of a metal heater box.

Why it fails: If the heater box is jarred or damaged, it could result in one or more of the heating coils inside to touch against the metal of the heater box.

If this happens, it can easily cause the element to ground, leading to the heater box staying ON continually.

How to fix: You first need to establish whether the element is carrying an electrical current. A simple multimeter is all you need to check for continuity. Begin by touching the meter’s probes together to ensure that you have feedback.

Your heater box may be single- or dual-coil, but the process for testing is essentially the same.

On a single-coil unit, you’ll need to remove the terminals connected to the heater box, place one probe on the metal heater box, and one probe on a terminal.

If your multimeter shows continuity, this lets you know that the element is indeed grounded and needs to be replaced.

For a dual-coil unit, you will first need to remove the wires. This will give you access to the terminals and allow you to test the connection to see if there is continuity.

Failed Cycling Thermostat

What is it: This thermostat is responsible for regulating the heat inside the clothes dryer. It does this by cycling the heat on and off.

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These parts are typically rated between 135 °F to 165 °F.

Why it fails: The contacts can fuse together, causing the dryer to get too hot. Because it doesn’t know to shut itself off, the cycling thermostat will continue to heat until the high-limit thermostat (see below) activates and shuts off the cycling thermostat.

How to fix: You can usually find the cycling thermostat located on the blower housing. This isn’t always the case, though, and could be by the heat source depending on the type of model you own.

To test it, simply remove it from the clothes dryer and attach your multimeter probes to the exposed terminals. In this instance, continuity is good.

However, you want to make sure that the thermostat isn’t breaking continuity when it heats up.

To check this, use a hairdryer on the thermostat while holding a thermometer against the cycling thermostat.

If your cycling thermostat is rated for 155 °F, for example, heat it past that point and check again for continuity. Always be sure to heat slowly.

If the multimeter reads that there isn’t continuity, your cycling thermostat is functioning properly and you can troubleshoot the next source.

If continuity breaks at a higher temperature, or there isn’t any at all, you’ll know that the unit is faulty and needs to be replaced.

Failed High-Limit Thermostat

What is it: This thermostat is responsible for shutting off the clothes dryer in the event that it gets too hot.

High-limit thermostats are rated for much higher temperatures, often 180 °F or more.

Depending on the model of your clothes dryer, the high-limit thermostat can be found next to the heating source or blower housing.

Why it fails: As with the cycling thermostat, the contacts can fuse together, causing the dryer to get too hot and not knowing when to shut off.

How to fix: To test it, simply remove it from the clothes dryer and attach your multimeter probes to the exposed terminals.

Just as with the cycle thermometer, continuity is good. However, you want to make sure that the high-limit thermostat isn’t breaking continuity when it heats up.

To check this, use a heat gun on the thermostat while holding a thermometer against the high-limit thermostat.

If your high-limit thermostat is rated for 250 °F, for example, heat it past that point and check again for continuity. Always be sure to heat slowly.

If the multimeter reads that there isn’t continuity, your high-limit thermostat is functioning properly and you can troubleshoot the next source.

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If continuity breaks at a higher temperature, or there isn’t any at all, you’ll know that the unit is faulty and needs to be replaced.

Failed Cycling Thermostat Bias Heater

What is it: the cycling thermostat bias heater is what allows the clothes dryer to be switched to multiple temperature settings using only one cycling thermostat.

It’s important to note that not all units have a bias heater. If your clothes dryer does, it will be built into the cycling thermostat, as its name suggests.

You should be able to tell if your dryer has a bias heater by examining the cycling thermostat. If you see two sets of terminals, you’ll know a bias heater is present.

Bias heaters allow the dryer to cycle at a lower temperature than what the cycling thermostat is rated for.

If it fails, it can result in the lower temperature setting to run hotter than what it is rated for.

Why it fails: The contacts can fuse together, causing the dryer to overheat.

How to fix: You first need to check to ensure what the ohm rating is by checking your dryer’s diagram (i.e., 5600 to 8400 Ω).

Once the rating is established, switch your multimeter to the ohm setting and touch its probes to the bias heater’s terminals.

If the multimeter shows that it isn’t within the established range, you will need to replace it.

Failed Thermistor

What is it: The thermistor is a sensor that lets the dryer know what the internal temperature is inside the drum.

They are designed to decrease resistance as the temperature increases.

Thermistor On The Right Side !!!

Why it fails: Improper ohm signal is being sent to the control board, resulting in overheating.

How to fix: Often located near the blower housing, this can easily be tested if your dryer has a built-in diagnostic mode.

If it doesn’t, check the diagram to find the ohm rating associated with the thermistor.

Simply remove the wires and attach your probes. If the reading is within range, the thermistor isn’t the issue.

Failed Blower Wheel

What is it: Finally, the blower wheel is what circulates the warm air within the dryer and back out of the exhaust.

Why it fails: This can get clogged with lint and buildup, resulting in the dryer getting too hot.

How to fix: Located within the blower housing, you will need to remove the panel and check for buildup. You should also check the wheel to make sure that it spins properly and isn’t damaged.

Dryer Blower Wheel

Conclusion

Take your time and start with the easiest solution first. By following these steps carefully, you can eliminate each potential issue and pinpoint the root cause of your dryer overheating.

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