Microwaves sit in an unusual spot among kitchen appliances. Some are inexpensive boxes you can replace in an afternoon, while others are built into cabinetry and double as the ventilation hood for your stove. The right answer to "is it worth repairing?" depends far more on which type you own than on the particular symptom. Start by identifying yours.
Three kinds of microwave, three different answers
Countertop microwaves
These plug into a standard outlet and sit on the counter. They are mass-produced, widely available and easy to swap. Unless the fix is simple, such as a failed door switch, a blown line fuse or a worn turntable coupler, replacement is usually the practical choice. Major components like the magnetron or control board often approach the cost of a new unit once labor is included.
Over-the-range microwaves
Mounted to the wall and upper cabinet above the cooktop, these combine a microwave, a vent fan and a cooktop light. Replacing one involves removing the old unit from its mounting plate, possibly installing a new plate, matching the cabinet width and vent configuration, and sometimes patching the wall. Because of that, repairing an over-the-range unit is frequently worthwhile, especially when it is less than about six or seven years old.
Built-in microwaves and microwave drawers
These are installed in a cabinet or wall cutout, often as part of a matched kitchen suite. Their size and trim must match the opening. Repair is often the sensible route as long as parts are available for the model.
A safety warning you should not skip
Microwaves contain a high-voltage capacitor and transformer. The capacitor can retain a dangerous, potentially lethal charge after the microwave is unplugged. Do not remove the outer cabinet or attempt to test internal components yourself. The checks below are limited to things you can do from the outside.
Symptoms, causes and safe checks
Completely dead, no display
- Check the outlet with another small appliance, and check the breaker or GFCI outlet if your kitchen has one.
- Unplug the microwave for a few minutes, then plug it back in. Monsoon-season outages and surges sometimes leave electronics in a confused state.
- If it is still dead, likely causes include a blown internal line fuse, a failed door switch that blew the fuse, or a failed control board. A blown fuse often indicates another fault, so it needs proper diagnosis.
Runs, but does not heat
The light comes on, the turntable spins and the timer counts down, but food stays cold. The usual suspects are in the high-voltage section: magnetron, diode, capacitor, transformer or a high-voltage fuse. This is technician territory only. On a countertop unit, this repair is often a reason to replace. On an over-the-range unit, it can be worth fixing depending on age and condition.
Starts, then stops
A microwave that shuts off after a few seconds may have a door switch out of alignment, a failing control, or an overheating condition. Make sure nothing blocks the vents on the top, back or sides of a countertop unit.
Sparking or arcing
- Remove anything metallic: foil, twist ties, travel mugs, dishes with gold or silver trim.
- Look at the waveguide cover, a small panel usually on the right inside wall. If it is burned or caked with grease, food residue can arc. Some covers can be replaced from inside the cavity.
- Check the cavity walls for chipped paint. Bare metal spots can arc and should be evaluated.
Turntable does not turn
Make sure the glass tray sits correctly on its roller ring and the coupler underneath is not cracked. If the tray is seated and still does not turn, the small turntable motor may have failed, which is a minor repair.
Keypad does not respond
Some buttons failing while others work points to the touchpad membrane or control. Grease and steam from cooking can contribute to touchpad failure on over-the-range models.
Vent fan or light problems on over-the-range units
The vent fan and cooktop light can fail independently of the microwave function. A fan that runs on its own sometimes turns on automatically because a thermal sensor detects heat from the cooktop below, which is normal. A fan that will not run at all, or that rattles, may have a failed motor or a loose blade.
Dust, grease and the over-the-range filter
Over-the-range microwaves pull cooking grease through metal mesh filters underneath. Desert dust that finds its way indoors combines with that grease into a sticky film, so the filters load up and the fan works harder. Soak the metal filters in hot water with a degreasing dish soap monthly if you cook often. If your unit recirculates air back into the kitchen rather than venting outside, it also has a charcoal filter that cannot be washed and should be replaced periodically.
Repair or replace: a quick framework
- Countertop, simple external or door-switch fix: repair may make sense.
- Countertop, no heat or dead control board: replacement is usually the practical choice.
- Over-the-range or built-in, under about six to seven years old: repair is often worthwhile for most failures.
- Over-the-range or built-in, near the end of a typical life with a major failure: compare with replacement, keeping in mind the cost and effort of installation.
- Any microwave with a door that does not close properly, a cracked door glass, or a damaged door seal: stop using it until it is repaired or replaced.
Microwave efficiency does not vary as much between models as it does with refrigerators or washers, so energy savings are rarely a strong reason to replace.
When to call for service
Call a technician for any no-heat problem, repeated fuse failures, sparking that continues with nothing metal inside, or a door that does not latch. ProFix Appliance Repair Las Vegas handles microwave repair for over-the-range, built-in and drawer models from all major brands. If the cooktop below is also giving you trouble, we can look at it on the same visit through our cooktop repair service. See where we work on our service areas page.