A microwave is the one kitchen appliance where we'd ask you to keep the screwdriver in the drawer. Even unplugged, the high-voltage capacitor inside can hold a charge strong enough to kill. So this guide is about what you can safely check from the outside, what the symptoms mean, and how to decide whether a repair is worth it.
Three kinds of microwave, three different decisions
Countertop models
These plug into any outlet and are easy to replace. Unless it's a high-end model, a countertop microwave with a serious internal fault is often cheaper to replace than to repair. Minor problems like a broken turntable coupler are a different story.
Over-the-range models
In a lot of Northern Virginia condos and townhouses, the over-the-range microwave is also the range hood. Its fan and light pull steam and smoke off the cooktop, sometimes through a duct to the outside and sometimes back into the kitchen through a charcoal filter. It's bolted to the wall and the cabinet above, it's sized to the opening, and replacing it is a bigger job than it looks. That tips the balance toward repair more often.
Built-in and drawer models
Built-in microwaves with trim kits, and microwave drawers like those made by Sharp and several other brands, sit in custom cabinet openings. They cost more, they fit a specific space, and they are frequently worth repairing.
Symptoms and what they usually mean
It runs, the light's on, the turntable turns, but food stays cold
This is the classic heating failure. The usual suspects are the magnetron, which generates the microwaves, the high-voltage diode, the capacitor or the transformer. Sometimes a failed door switch or control is to blame. All of these live inside the high-voltage section, and none of them are a DIY repair.
Completely dead: no display, no light
Check the outlet first by plugging in a lamp. Look for a tripped breaker or GFCI. If the outlet is fine, the cause may be an internal fuse, a thermal cutoff or a failed door switch. A blown fuse often has a reason, like a failing door switch, so replacing the fuse alone may not last.
Sparks or arcing inside
Stop using it right away. Common causes include metal in the cavity: foil, a twist tie, or dishes with metallic trim. A grease-soaked or burned waveguide cover, a small panel usually on the side wall of the cavity, can also arc. So can chipped paint inside the cavity, where bare metal is exposed. A burned waveguide cover can often be replaced, but have the unit checked if the arcing continues.
The turntable won't turn
Look for a misaligned tray, a broken coupler under it, or food debris jamming the roller ring. If those are fine, the turntable motor may have failed.
The vent fan or light doesn't work on an over-the-range unit
Clean or replace the grease filters. Check the bulbs. If the fan hums but won't spin, or runs only at one speed, the fan motor or its control may be failing.
Buttons stop responding
A touchpad that ignores some keys often has a failed membrane or a control board fault. Some models also have a child lock, often set by holding a particular key, which can make the panel seem dead. Check the manual before assuming the worst.
It runs on its own or won't stop
Unplug it and leave it unplugged. A shorted touchpad or failed control can start the unit by itself. Don't use it again until it's been checked.
Safe checks for owners
- Plug a lamp into the same outlet to confirm there's power.
- Reset the breaker or GFCI if one has tripped.
- Check the door for damage, and make sure it closes firmly. A microwave with a bent door or broken hinge shouldn't be used.
- Clean the inside, including the waveguide cover, with mild soap and water.
- Check the turntable, coupler and roller ring.
- On an over-the-range model, clean the grease filters and check the bulbs.
Don't remove the outer cabinet, and don't run the microwave empty to test it. Running it with nothing inside can damage the magnetron.
When it's worth a repair
A few questions help. How old is it? What kind is it? Is the problem a small part, like a door switch or a light, or a major one? Is the model still supported with parts? A built-in or over-the-range unit in good shape with a failed magnetron or fan may well be worth fixing. A basic countertop model with the same problem usually isn't. We'll tell you plainly when a repair doesn't make sense. Our guide on deciding whether to repair or replace an appliance goes into more detail.
Habits that help a microwave last
Most microwave failures can't be prevented, but a few habits help. Wipe up spatters while they're fresh, since baked-on grease on the waveguide cover is what eventually burns and arcs. Close the door gently rather than slamming it, because the latch hooks and door switches take every hit. On an over-the-range unit, run the vent fan whenever you cook on the burners below, and clean or swap its filters on the schedule in the manual. Steam and grease the fan doesn't carry away end up in the controls above.
What a visit involves
We test the microwave in your kitchen, tell you what's gone wrong, and quote a price you can accept or turn down before anything is replaced. Parts are ordered against the model number, and if one isn't made by the original brand, you'll know. More information is on our microwave repair page, and if yours is a GE, see our page on GE microwave repair.
Common questions
Is it safe to use a microwave with a cracked door window?
No. Stop using it until the door has been inspected and repaired or the microwave replaced.
My microwave stopped working after a power outage. Why?
A surge when power returns can damage controls or blow a fuse. Check the breaker and outlet first. There's more on what to check after the power comes back.
Can I install a new over-the-range microwave myself?
Some people do, but it involves mounting to a wall plate and the cabinet above, electrical connection and sometimes venting changes. Follow the manufacturer's instructions closely, and get help lifting it.