Microwaves are the appliance people replace without thinking — they’re relatively cheap, ubiquitous, and a new countertop unit runs $150. But not every microwave is a countertop unit. Over-the-range microwaves, drawer microwaves, built-in trim-kit microwaves, and convection combi microwaves routinely cost $800-$2,500, and replacement means matching hood venting, drawer cabinetry, or custom trim kits that may no longer be available. For those units, repair usually makes more sense.
Advanced Home Appliance Repair services all microwave types with a focus on integrated and built-in units: over-the-range models, drawer-style units from Sharp, Wolf, and Thermador, and custom-trim microwaves from GE Monogram, KitchenAid, and Bosch. Because microwave repair involves high-voltage circuits (up to 4,000 volts in the magnetron circuit), it’s work best left to trained technicians — not a DIY project even for handy homeowners.
Microwave Not Heating Food
This is 60% of our microwave calls. Causes, in order of frequency: failed magnetron (the tube that generates the microwaves — wears out after 8-12 years of heavy use), blown high-voltage diode (cheaper part, common failure), failed high-voltage capacitor (rare but possible), or a door interlock switch that’s stuck open (a safety device that prevents the magnetron from firing when the door isn’t confirmed closed). We carry the universal parts that fit most models and can replace a magnetron on-site in most cases. Key point: capacitors store lethal voltage even unplugged, so always have a trained technician discharge before any work.
Other Common Failures
Turntable won’t rotate
Turntable motor failure or broken drive coupler. The motor is a small synchronous AC motor tucked below the cavity floor. Easy replacement, usually under $100 parts and labor combined. We carry universal couplers for most mainstream brands.
Sparking inside the cavity
Stop using the microwave immediately. Causes: damaged waveguide cover (a mica sheet on the interior right wall that protects the microwave entry point — if it’s burned or broken, replace it); metal item inadvertently left in the cavity; or failing magnetron venting arcing. We inspect the waveguide, interior paint coating, and magnetron output. If the cavity paint is chipped down to bare metal, that’s an arcing risk — we touch it up with microwave-safe ceramic paint.
Control panel unresponsive or dim display
Failing display board, failed transformer on the low-voltage side, or bad membrane switch. We test display voltage supplies and replace the specific failed component. On over-the-range units, there’s often a vent light and fan functionality on the same board — those continue working is often a clue that specific display circuits have failed rather than the whole control.
Runs constantly even with door open
Stuck door interlock relay or welded contact in the primary interlock. This is a safety issue — magnetron could theoretically fire with the door open, exposing you to microwave radiation. We disconnect power and replace the interlock assembly immediately. Do not use the microwave until this is fixed.
Over-the-Range Units: Vent and Light Issues
OTR microwaves do double duty as range hoods. When the vent fan won’t turn on, the issue is almost always the fan motor or the capacitor that drives it. Light bulbs (both cooktop and interior) fail often and are a quick fix. The charcoal filter (if your unit recirculates rather than vents outside) should be replaced every 6-12 months — we replace it during service if you want.
Drawer Microwaves (Wolf, Sharp, Thermador)
Popular in Fairfax County kitchen remodels — they install at counter height beneath the counter, eliminating the overhead microwave cluttering the sightline. Drawer units add mechanical complexity: a motorized drawer that opens and closes on rails, safety interlocks on the drawer mechanism, and a sealing gasket around the cavity. We service all three plus the standard electrical components. Drawer motor failures and rail track issues are the most common service call.
Convection and Combi Microwaves
Advantium (GE), Speed Cook (Bosch), combi-steam microwaves from Miele — these have a microwave magnetron plus a heating element and convection fan. More parts, more failure modes, but the same diagnostic discipline. We service them all.