Dryers have many parts that can go bad. Two such part are the thermal (limit) fuse and the thermal cutoff.
In past years, house fires were commonly caused by failed dryers.
However, thanks to these components, this is a thing of the past, as both parts work to prevent fires.
Let’s take a look at some common issues with both the thermal fuse on the blower wheel and cutoff fuse on the heater assembly.
We’ll discuss some troubleshooting and possible fixes.
Thermal (Limit) Fuse On The Blower Wheel
This particular thermal fuse is located on your dryer’s blower wheel.
It monitors the temperature of the dryer, and when that temperature gets too high, it shuts power off to the motor (not to the heating element !!!)
Diagnosing a tripped thermal fuse is easy. You just need to have a multimeter and check continuity between two contacts.
But first, turn the dryer 240V power cord OFF from the wall and only then start to work on the dryer.
Every dryer has its own procedure on how to disassemble it and how to reach this fuse.
Failed Relay on the Control Board
Another common reason for Whirlpool and Maytag dryers, that this particular thermal fuse keeps tripping is due to a failed relay on the control board.
Usually, this relay becomes stuck in the “ON” position and sends the power to the heating element, ignoring ON/OFF commands from the control board.
This will cause the control board to constantly send power to the heating element while dryer running.
It will not send the power if the dryer is not running !!!
When the critical temperature is reached, the thermal fuse blows. Usually, this is happening at the end, when the dryer goes to the Cool Down cycle.
When this occurs, you’ll need to replace the thermal fuse and entire control board, because the relay is stuck.
Here’s how to check the control board:
- Unplug the dryer
- Remove the screws on the back of the machine that hold the control panel in place
- Flip the control panel over to expose the control board
- The relay switch should be on the lower right of the board
- Check for any melting or black marks to indicate it has failed
- If there is nothing visible, change control board anyway
The Thermal Fuse is Wrapped with Lint
Lint can bypass the trap sometimes, and end up in the wrong places inside your dryer.
Once such place it can end up is wrapped around the thermal fuse inside the blower wheel.
When this occurs, it will cause the fuse to overheat and blow due to heat build-up.
If this is the issue, you’ll need to access the blower wheel and clean all lint and other debris from around it.
Then you will need to locate and replace the thermal fuse.
To make it easier to locate, keep in mind that the blower fan is attached to the drive shaft motor.
Thermal Cutoff (heater Assembly) Fuse Keeps Tripping
The thermal cutoff is located on the heater assembly and it controls the temperature of the dryer.
It also helps monitor the amount of heat being produced by the dryer.
If you notice that the drum spins but there’s no heat produced, the thermal cutoff switch is probably blown.
You may also notice that your dryer is producing a small amount of heat, but not enough to dry your clothes in a timely manner.
You can troubleshoot the thermal cutoff by testing it for electrical continuity. However, you’ll also have to determine what made it fail in the first place.
Here are the most common reasons a thermal cutoff fuse will keep tripping.
Dryer Hose or Vent Line Clogged
When dryer hoses or vent lines become clogged it prevents proper air circulation, which will eventually cause your dryer to overheat.
This is the most common reason a thermal cutoff fuse keeps tripping.
You need to remove the vent line from the back of your dryer and clean it out.
Here’s the easiest way to clean the dryer vents:
- Unplug the dryer
- Locate the vent on the back of the machine
- Remove any clamps or tape holding the vent to your dryer
- Move the dryer out of the way to give you room to work
- Clean the duct from the interior side of the vent. This will be behind your machine in the laundry room
- Once that’s as clear as you can get it, you’ll need to locate the exterior vent on the outside of your home
- This area is easy to access by removing the duct cover or flap
- Be sure to clear the entire line, this may take a few tries depending on how many twists and turns your duct work has
- Once you feel confident that all lint is removed, reconnect everything
Sometimes you can discover bird nest on the very end of the vent line.
Heating Element Grounded
When the coils in the heating element expanding, they can touch metal casing and it can cause the heating element to become grounded.
When this occurs it will cause your dryer’s heating element to remain “ON” constantly, even during the fluff or AIR ONLY cycle.
Cycling thermostat just not able to control amount of heat produced by the heating element.
Eventually, this will cause your dryer to overheat which will trip the thermal cutoff fuse.
To repair this problem you will need to follow these steps:
- Unplug the machine
- Remove the back panel from the dryer
- The heating element will be located near the bottom of the machine, you’ll need to disconnect the wires going to it
- Mark the location of each wire, so you can remember where they go later
- Remove the high-heat thermostat from the old heating element and transfer it to the new one
- Position the new heating element to the heater box properly and screw into place
- Replace the wires and back panel
- Plug the dryer in and test to see if it’s working properly
In the end, anytime the thermal fuse or cutoff trips, it will need to be replaced.
As a one-time use part, it’s not designed to be reset.
Also, remember to track down the actual problem when this fuse blows.
The simple fact is, it doesn’t happen for no reason at all.
Have you had issues with a thermal fuse tripping?
What brand machine do you have and what was causing the problem? Comment now and let us know.