Where the fuse is and why it blows

The fuse in your microwave sits inside the cabinet, usually near the power cord entry or on the control board. It is a small cylindrical component, typically 1 to 2 inches long, that looks like a tiny metal-capped tube. When you turn on the microwave and it does nothing — no light, no beep, no hum — a blown fuse is often the cause.

A fuse blows when too much electrical current flows through it. This happens when the microwave draws more power than the circuit can handle, or when an internal component fails and creates a short. Unlike a circuit breaker, a fuse cannot be reset; it must be replaced.

Before you open the cabinet, unplug the microwave from the wall outlet. Even with the power off, some components inside hold an electrical charge and can cause injury. Wait at least five minutes after unplugging to let capacitors discharge.

Key Takeaways

  • The fuse is a small cylindrical component inside the microwave cabinet, usually near the power cord or control board.
  • You must unplug the microwave and wait five minutes before opening it, because internal components can hold a dangerous charge even when powered off.
  • Replacement fuses cost between $5 and $15 and are rated by amperage — you must match the amperage of the blown fuse exactly.
  • If the microwave blows a second fuse shortly after replacement, an internal component has likely failed and the microwave may not be worth repairing.

Finding the right replacement fuse

The blown fuse will have a label printed on its metal cap showing its amperage rating — typically 15A, 20A, or 25A. Write down this number. You must buy a fuse with the exact same amperage rating. Using a higher-rated fuse defeats the purpose of the fuse and can damage the microwave or create a fire hazard.

Take the blown fuse to an electronics supplier, hardware store, or appliance parts retailer. Many will have the replacement in stock. You can also order online using the fuse amperage and the microwave model number. The replacement will cost between $5 and $15. Buy a fuse rated for microwave use, not a general-purpose fuse, because microwave fuses are designed to handle the specific power demands of the appliance.

If you cannot read the amperage on the blown fuse, look up your microwave's model number online or in the manual. The manual will list the correct fuse rating. The model number is usually printed on a sticker inside the cabinet or on the back of the unit.

Opening the microwave cabinet safely

Unplug the microwave and wait five minutes. Locate the screws holding the cabinet together — they are usually on the back or bottom of the unit. Use a screwdriver that fits the screw head snugly; a loose fit can strip the screw and make reassembly difficult.

Remove all visible screws and set them aside in order. Some microwaves have a metal cover plate over the fuse holder; if yours does, remove the screws holding that plate as well. Do not force any panel or cover. If something does not come loose after removing all visible screws, look for hidden fasteners under stickers or trim.

Once the cabinet is open, locate the fuse holder. It is usually a small cylindrical socket with the fuse inserted horizontally or vertically. The fuse may be held in a clip or a threaded socket. Do not touch any other components inside the microwave, especially the large cylindrical capacitor, which can deliver a dangerous shock even hours after the unit is unplugged.

Removing and installing the fuse

Gently pull the blown fuse straight out of its holder. If it is held in a clip, it will slide out with light pressure. If it is in a threaded socket, turn it counterclockwise until it comes free. Do not force it; if it is stuck, explore a small amount of penetrating oil and wait a few minutes.

Insert the new fuse into the holder in the same orientation as the old one. If the old fuse was horizontal, insert the new one horizontally. If it was vertical, insert it vertically. Push or turn gently until the fuse is seated firmly. You should hear or feel a slight click if it is a clip-style holder.

Reassemble the cabinet by replacing all screws in reverse order. Tighten them snugly but do not over-tighten, which can crack the plastic housing. Replace any cover plates or trim you removed.

Testing and what to do if the fuse blows again

Plug the microwave back into the wall outlet. Press the power button or set a short timer to test it. The light should come on, the fan should run, and the display should show the time or a menu. If the microwave works normally, the fuse replacement was successful.

If the microwave does not power on after the fuse replacement, unplug it when ready and check that the fuse is seated correctly. Reseat it by removing and reinserting it. If it still does not work, the fuse may have been installed backward or the wrong amperage may have been used. Check both and correct them if needed.

If the microwave powers on but the fuse blows again within a few days or weeks, an internal component has likely failed. A second blown fuse suggests a short circuit or a failed capacitor, compressor, or transformer. Repairing these components usually costs $150 to $400, which may exceed the value of the microwave. At that point, replacement is often the more practical choice.

When not to replace the fuse yourself

If you are uncomfortable working inside electrical appliances, or if you have never done this type of repair, consider having a technician do it. The risk of electrical shock is real, and mistakes during reassembly can create safety hazards. A service call typically costs $75 to $150 plus the cost of the fuse.

Do not attempt this repair if the microwave is still under warranty. Opening the cabinet will void the warranty, and the manufacturer may refuse to cover future repairs. Check the warranty documentation or contact the manufacturer before you start.

If the microwave is very old or has other problems — such as a cracked door, a broken turntable, or a heating element that does not work — replacing the fuse may not be worth the effort. Weigh the cost of the repair against the age and condition of the unit.

Frequently Asked Questions

Can I use a higher-amperage fuse if I do not have the exact rating?

No. A higher-amperage fuse will not blow when it should, which means internal components can overheat or fail without protection. This creates a fire hazard and can damage the microwave permanently. Always match the amperage exactly.

What if I cannot find the fuse after opening the microwave?

Check the manual for your model number or contact the manufacturer's customer service line. They can tell you the fuse location and rating. Some older or compact microwaves have the fuse in an unusual spot, such as inside the control panel or mounted vertically on the back wall.

Is it safe to touch the fuse holder while the microwave is unplugged?

Yes, as long as you have waited at least five minutes after unplugging. The fuse holder itself is not a shock hazard. Avoid touching the large cylindrical capacitor or any wires connected to it, as these can hold a charge.

How long does a microwave fuse usually last?

A fuse should last the life of the microwave if the unit is working correctly. If a fuse blows once, it is usually a one-time event caused by a power surge or a temporary overload. If fuses blow repeatedly, an internal component is failing.

Can I test the fuse to see if it is actually blown?

You can use a multimeter set to the continuity or resistance setting. Touch the probes to each end of the fuse. A working fuse will show continuity or very low resistance. A blown fuse will show no continuity or infinite resistance. If you do not have a multimeter, visual inspection usually works — a blown fuse often has a dark mark or discoloration inside the glass or plastic casing.