Microwave repair: what to know

What the job involves, what changes the price, and what to ask a pro.

What microwave repair is

Microwave repair diagnoses a unit that does not heat, sparks, runs without heating, or has a broken door latch or control panel. Many faults involve high-voltage parts such as the magnetron, high-voltage capacitor and diode, which hold a dangerous charge even when unplugged, so this work is for trained technicians.

Signs you need it

  • The microwave runs and the turntable spins, but food stays cold
  • You see sparks or arcing inside the cavity, often from metal or a damaged waveguide cover
  • The door does not latch, or the display stays on with the door open
  • The panel buttons do not respond, or the display flickers
  • The unit hums loudly, buzzes or blows a fuse when it runs
  • Heat or a burning smell comes from the vents or the back panel

What the pro does

  • Confirm the model and check the door switches, latch and hinges for alignment and damage
  • Test the control panel, the fuse and the interlock switches with a meter, after safely discharging the unit
  • Check the magnetron, high-voltage capacitor and high-voltage diode with the meter and with proper test procedures
  • Inspect the waveguide cover and the cavity for damage, burn marks and food debris
  • Replace the failed part, such as a door switch, fuse, diode, capacitor or magnetron
  • Run a test heat cycle with a load of water to confirm the unit heats and the door interlocks work

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Which part failed, since a door latch or fuse is far simpler than a magnetron or high-voltage capacitor
  • Brand and model, and whether the parts are stocked
  • Whether the unit is built-in or over-the-range, which affects access
  • Age of the unit and whether replacement is the more sensible choice
  • Whether a part must be ordered, which can mean a second visit
  • Damage to the cavity or waveguide cover that needs replacing

What a written quote should spell out

  • Make, model and serial number, and any symptoms and error codes noted
  • Each failed part by name and the test that confirmed it
  • Confirmation that the high-voltage parts were tested with the correct procedure
  • Warranty on the parts and the labor, in writing
  • Confirmation that the door interlocks and a test heat cycle were checked before the pro left

Questions to ask before you hire

  • Are you trained to work on the high-voltage parts, and how do you discharge the unit?
  • What part do you think failed, and how did you confirm it?
  • Do you carry the magnetron, capacitor or diode for my model?
  • Will you check the door interlocks before you leave?
  • Is it worth repairing an older microwave?
  • Does the warranty cover the part and the labor?
  • Will you run a test heat with a load of water before you leave?

Red flags

  • A pro who opens the cabinet without discharging the high-voltage capacitor
  • Replacing the magnetron before testing the fuse, diode and door switches
  • A unit returned with the door interlocks bypassed
  • No test heat cycle before the pro leaves
  • A quote with no part names, only a general microwave repair line

What you can do yourself

Unplug the microwave and do not use it until it is repaired. You can safely clean the door seal, check that the door closes squarely, and wipe the cavity of food debris. Do not open the outer cabinet, touch the high-voltage capacitor, the magnetron or the diode, or run the unit with the cover off; call a pro for any heating, spark, fuse or high-voltage fault.

Licenses and permits

Microwave repair is often not a licensed trade, but work on high-voltage parts is generally left to trained technicians, and a new electrical connection can need a licensed electrician. Check state and local rules with your licensing agency before hiring.

Microwave repair questions

Why does my microwave spark?

Sparks usually come from metal in the cavity, a damaged waveguide cover, or food residue on the walls. Stop using the unit and have a pro inspect it before you run it again.

Is it safe to use a microwave that sparks or hums loudly?

No. Stop using it, unplug it, and have it inspected. High-voltage parts can fail in ways that are dangerous to use.

How does infinibell work?

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About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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