Hot beverage inside a microwave

Over-the-range microwaves are built into the cabinetry and bolted to a wall, so replacing one that conks out is no simple chore. To avoid replacing yours more than about once every 10 years—which is how long most manufacturers tell us they should last—you’ll want to take good care of it. 

Your microwave may not get as grimy as your oven, but even so, one of the best ways to keep it humming along is to keep it clean. That means wiping down the interior when your teenager heats up a bowl of pasta without covering it, and regularly cleaning the grease filters that catch the cooking fumes from the rangetop, especially if you often fry food.

When Consumer Reports asked its members about their experiences with more than 37,000 over-the-range microwaves purchased between 2008 and 2018, people who had the appliance repaired reported paying about $103 to get it fixed. To avoid the hassle—and expense—of a repair, here are some simple things you can do on a daily or weekly basis to make your microwave last.

1. Be quick with the cleanup. Sponge up spills as soon as they occur. Bits of food left behind can absorb some of the microwave’s energy when you turn it on again, creating a hot spot that can damage the interior. Take special care not to scratch the protective mesh inside the door if it’s exposed, because it prevents microwaves from escaping and zapping you.


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2. Turn on the exhaust fan. An OTR’s exhaust fan isn't as efficient as a range hood’s, but you should use it anyway. “Many times the user will not turn on the exhaust when cooking on the range cooktop, causing the moisture rising from pots and pans to collect on the electronics of the microwave and shorten its life span,” says Wayne Archer, a technical expert at Sears Home Services. If moisture collects, wipe it off with a paper towel or soft cloth.

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3. Degrease the grease filter. It’s easy to forget these filters on the underside of the microwave, which trap steam and cooking fumes. But if you let them get too gunky, they can cause your microwave to run less efficiently and pose a fire hazard. They’re easy to slide out to clean, but you may want to slip on some rubber gloves before you do. Soak the filter in a sink filled with hot water and a degreasing dish detergent such as Dawn. Some manufacturers say you can put them in a dishwasher, but check your owner’s manual first. If your filter no longer fits snugly, replace it.

4. Don’t slam the door! Your microwave door has three (sometimes four) safety interlock switches that disable the oven when the door is open. For the microwave to work properly, the switches have to line up with their corresponding latches when the door is closed. “All the door strikes, latch mechanisms, and door switches themselves are plastic, so slamming the microwave door can physically break any of these components,” says Chris Zeisler, technical service supervisor at RepairClinic.com. “The series of switches all have to work in unison.” Damage to any of the switches or latches could render the microwave inoperable.

5. Don’t run it empty. Some people mistakenly run their microwave empty when they just meant to use the timer. If this happens for just a short time, no harm done. “But with nothing in the microwave, there are no [water molecules] to excite and the unit can overheat quickly or cause burn marks in the interior,” says Zeisler. “The microwaves can concentrate in one section of the cavity, causing damage.”

6. Avoid most metals. Metal reflects microwaves, whereas glass, paper, plastics, and most ceramics allow them to pass through to the food. Putting metal utensils or dishes with metal trim or silver or gold plating in a microwave can cause arcing—actual sparks flying. If the metals are touching the sides of the interior, the arcing can burn a hole in the cavity wall, damage that's not repairable. So keep at least an inch of clearance on all sides of your food. Some manufacturers say you can use a small amount of aluminum foil in a microwave, but only if it’s folded tightly around the food. If you want to try that, check the microwave manual first. Protruding pieces of foil or the metal from twist ties can act as an antenna and cause arcing that damages a microwave.

7. Use preprogrammed cooking times. To prevent food from overcooking and spattering the inside of the oven, use the presets. And be mindful of cooking times. “Too often we hear of a microwave meeting its maker because an incorrect cook time was input into the control system and the unit fried itself,” says Zeisler. “If you inadvertently set it at 50:00 instead of 5:00, you can damage the microwave.”

8. Don't attempt to repair the electronics yourself. Not that you necessarily would, but in case you’re tempted, consider that the Consumer Product Safety Commission has reported that people have been electrocuted trying to repair their microwaves. A microwave can hold an electrical charge at thousands of volts in its capacitors for hours or even days after it has been unplugged, according to RepairClinic.com. “The capacitor is a component that stores energy and releases it when needed,” says Zeisler. “This energy can be released when touched by a person.” RepairClinic.com advises leaving such repairs to a pro. But get an estimate first; it’s an expensive repair, and it may cost less to replace the appliance.

Editor's Note: This article also appeared in the August 2019 issue of Consumer Reports magazine.