How To Replace a Microwave Fuse

Microwaves are complicated appliances, and they can be a challenge to repair, even for experienced DIY’ers. However, there are several repairs that can be performed to keep your microwave running properly. For example, a microwave fuse is a part that commonly needs replacing, and with a little know-how and the right tools, you can install a new one to fix your appliance.

Safety Warning

Because of the high voltage and high current used by microwave ovens, be aware that repairing this appliance poses a substantial risk for injury or death if precautions are not taken. You should always unplug the microwave before you attempt any disassembly.  Since high voltage capacitors used in microwaves may retain a charge even after the microwave has been unplugged, we recommend that only experienced professionals access and replace internal components.

What kind of fuse do you need to replace?

A fuse is an electrical device that prevents too much current from passing through an electrical circuit. These are usually sacrificial components, meaning that they are damaged after being tripped and cannot be re-used. Microwaves usually contain several types of fuses for safe operation. A main fuse or line fuse is a fuse that will cut the flow of electricity if too much current passes through it. Conversely, a thermal fuse will prevent electrical flow if the fuse is heated to a specific temperature. 

Testing a Fuse

Before you replace a fuse, it is a good idea to test the part to make sure it is actually the cause of your problem. You can use a multimeter to test the part for continuity. A continuity test will determine if a continuous electrical path is present in the fuse. Before you begin, make sure the microwave is unplugged, but since high voltage capacitors used in microwaves may retain a charge even after the oven has been unplugged, it is recommended to discharge the capacitor before servicing. You can do this be placing a screwdriver blade across each set of capacitor terminals. You should avoid touching the blade when doing this.

Once you have removed the fuse from the microwave, touch the probes of your multimeter to each terminal of the part. If the meter reading shows zero ohms of resistance, the fuse has continuity. If the meter’s needle does not move, or the digital display does not change significantly, there is no continuity, which means the fuse has blown and will need to be replaced.

Be aware that the failure of the fuse often indicates that there is a shorted electrical component in the microwave, such as a failed door switch. This part will also need to be replaced, or the fuse will continue to fail.

Replacing a fuse

If you determine that the fuse is faulty, the next step is to replace the part. As with testing, be sure that the microwave is unplugged before beginning the repair. The first step of the procedure will depend on your model of microwave. If your fuse is located behind the control panel or vent grille, you may be able to access it without removing the microwave from its installation. You will need to remove the grille or control panel to access these fuses. If you cannot access the fuse you need from behind these panels, you will first need to uninstall the appliance. This can usually be achieved by removing 2 or more screws from the top of the microwave, then lowering it and lifting it off a mounting bracket. Set it on a sturdy surface, and then you’re ready to continue.

Next, you will need to remove the outer cover to reach the internal components. Fuses are located in many places inside the microwave, including the top, side, and behind the vent grille. Using the wiring diagram can help you locate the appropriate fuse. Once you have located the fuse, remove any necessary wires and fasteners to free it from the microwave.

To replace the fuse, connect any necessary wires to the new part, and secure it with any clips or fasteners if necessary. Replace the panels or covers and secure them with the screws. If applicable, carefully place the microwave on the mounting bracket, then align it with the cabinet, making sure the power cord is accessible through the top. Secure the screws, plug the microwave back in, and test the appliance to make sure its working properly.

Find the right microwave parts with Repair Clinic

To find the correct fuse for your microwave, simply type your model number into the Repair Clinic search bar. We carry parts for all major brands, so you’ll be able to keep your appliance running great, no matter the problem. You can also visit our repair help section for videos and articles that can further assist you in your repair.

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