Microwave oven repair and maintenance tips

The time and labor savings microwave ovens give make them one of our most used appliances. Choices we make when buying a unit and procedures we follow during installation, operation and cleaning can make a difference in their longevity and use.


  • It’s important for safety reasons and to follow many city codes to have a dedicated power supply to the microwave. Whether mounted over the range or used on the counter most units are 1500 – 1800 watts and require a 20 amp circuit breaker for safe operation. The supply wire used should be #12. Although circuit breakers offer protection for improper installation it’s important for the safety and operation of the wiring and the appliance itself. If you’re unable to dedicate a line to it a line that leads to a bedroom or other little used circuit should be used.
  • Depending on if it’s used heavily for cooking or only for warming things the vent fan should be faced either up for venting through the cabinet and through the roof or forward for ventilation through the front. Much thought should be given to venting through the roof because roof vents can leak and simply aren’t necessary for normal use. Over-the-range units usually come from the factory ready for front ventilation but it’s smart to check before installation. It’s also a good idea to test the oven and all the light and fan options while it’s sitting on the counter before installation because the fan and some interior lights require it be taken down to fix or replace.
  • Rather than using screws, at least 2″ lag bolts should be used to fasten the mount directly into 2 wall studs. Stud-finders are useful, inexpensive tools for this and many other DIY projects. When drilling into any wall the utmost care should be taken to ensure wires, plumbing stacks or other vents are avoided while mounting the plate. Failure to do this can result in constant odor, the need for electrical repair and/or even death from electrical shocks.


Use and Maintenance:

After the microwave is properly installed familiarize yourself with its operation with the owner’s manual and by the unit. DO NOT use a microwave without food or liquid inside because it can ruin the magnetron.

For over-the-range microwaves and especially if the home has high mineral content in the water, it’s a good idea to put clear tape over the very bottom of the door seal to keep moisture from boiling water and smoke from fried foods from staining or affecting the grid or staining the inside of the glass door.


Keep the owner’s manual for future reference for repair or maintenance advice. Some parts, such as the magnetron, transformer and main control are very expensive to replace and may be covered by warranty. This is usually a limited warranty for covering parts but not labor. Installing these parts wrong can ruin other parts to cause multiple repair attempts. Factory authorized service will need to be used for service to get authorization for those parts.

  • Unless you are very familiar with microwaves DO NOT work on them. Some older models, even unplugged, can have capacitors that may discharge stored electricity and cause very serious damage to fingers.
  • Unplug or cut the power to any appliance before working on it.
  • If the microwave or really any other appliance with an electronic control stops working it’s best to unplug it or shut off the circuit breaker for at least ten minutes. Very often the control will reset itself to come back up. There are fuses in the control panel that can be easily accessed without taking the outside cover off but again, if you’re unfamiliar it’s best to call a professional for this appliance. If working on any electronic control panel an electrostatic wrist strap should be used to avoid static electricity that can ruin the control. This is especially important in dry climates and in winter months when static electricity is more prevalent. If a strap isn’t available try to keep a bare hand grounded at all times.
  • Bumping noises that seem to come from the turntable can be caused by something as minor as a tray roller having food particle buildup that can be removed by scraping it with a fingernail to a worn turntable motor that is accessed from the bottom panel without removing the unit
  • Explain to all family members that rings on fingers can make scratches on even metal door handles and everyone should consider this when using it.

These tips will help to have a properly installed and maintained microwave for years of use and enjoyment.

Posted in Microwaves.