How to Tell If a Thermal Fuse Is Blown

Thermal fuses are fire-prevention safety components that can be found in most modern appliances. The function of a thermal fuse is to prevent the appliance from heating beyond a specified maximum temperature by stopping the flow of electricity before it reaches the heating element. Because a faulty heating element can also result in an appliance that fails to produce heat, you should always test your thermal fuse to ensure that it is actually blown before attempting to replace it. If you suspect that a thermal fuse is blown in an appliance, avoid using the appliance until the blown thermal fuse has been replaced.

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How to Tell If a Thermal Fuse Is Blown

The Early Steps

Before doing any testing, be sure to unplug the appliance from its electrical source before attempting to troubleshoot the thermal fuse. Make sure that all electricity or gas has been disconnected from the appliance before moving forward, and if your appliance is particularly expensive or complex, consider contacting the manufacturer to inquire about repair service, if your appliance is still under warranty. Troubleshooting or repairing a warrantied appliance may violate the terms of your warranty. Consult your appliance's user manual to determine where the thermal fuse is located. Contact the manufacturer if you are unable to find this information in your user manual. Note that thermal fuse locations can vary between brands, appliance types and models; the most common thermal fuse locations are behind the bottom toe or rear appliance panels.

Thermal Fuse Access

Once you've located the placement of the thermal fuse, remove the appropriate panel to access the fuse in your appliance. Access thermal fuses located behind the rear appliance panel by removing the four corner screws that hold the panel in place. Access thermal fuses positioned behind the bottom kick appliance panel by using a putty knife to press on the metal clips at the top of the panel until they release. Examine the exposed appliance components to locate the thermal fuse. Look for an approximately 1-inch piece of white plastic with two wires attached. Disconnect the wires from the thermal fuse by gently pulling on them. Like when testing dryer parts for continuity, once the fuse is disconnected, you can test it with a multimeter.

Is the Thermal Fuse Blown?

Press the appropriate button to power on your digital multimeter. Turn the control dial to set the multimeter to read Rx1 resistance. Touch the left multimeter lead to the left side of the thermal fuse; touch the right multimeter lead to the right side of the fuse. Keep an eye on the multimeter needle; a needle that fails to move indicates a blown thermal fuse. If this is the case, don't fret: thermal fuse replacement is a simple task.