Microwave Light Not Working? Test The Light Socket

Home » Microwave Light Not Working? Test The Light Socket

So you’ve just discovered your microwave’s cavity light has stopped working. This may not seem like a problem you need to address right away, but before long you’ll start becoming annoyed that you can’t see the food you’re attempting to heat up! Has the light bulb simply burned out or has the LED light fritzed out? That’s the most likely cause. But if the light itself doesn’t appear visibly damaged, it’s possible the light socket is not receiving sufficient voltage to power the light. In this article, Repair Clinic will guide you through testing the light socket to help determine the exact cause of the microwave light not working.

How can I reach the microwave cabinet or cavity light?

To test the light socket for the microwave’s cabinet or cavity light, you’re going to need to be able to reach the component. Before you begin any disassembly, be sure to unplug the appliance’s power cord (usually found in an overhead cabinet for microwaves installed over a range) or shut off the power supply.

The cabinet light is located on the bottom of the microwave

Most over-the-range microwaves will have a cabinet light that can be used to help illuminate your range’s cooktop. The cabinet light is located on the bottom of the microwave and can be reached by simply unthreading a screw to release the lens cover from the base of the unit. With the lens cover detached, unthread the light bulb from the socket. If your microwave uses an LED light board, unthread the screw or screws to release the board then disconnect the wire connector. Inspect the bulb or light board for any visible signs of damage such as a broken filament or burn marks.

A microwave oven cavity light will usually be found in a small space next to the interior cavity

A microwave oven cavity light will usually be found in a small space right next to the oven’s interior cavity (logically!). For over-the-range microwaves, the cavity light can normally be accessed by first uninstalling the top vent grille. Next, remove the unit’s charcoal filter and detach the lamp cover that is usually found underneath the charcoal filter. For stand-alone microwaves, you may need to remove the front control panel or the appliance’s cover to access the cavity light*. Once the light is exposed, you can reach into the lamp compartment and unthread the cavity light bulb or remove the screw or screws to release the LED light board. Again, disconnect the wire connector, if applicable, and inspect the bulb or light board for damage. Not seeing any broken parts or tell-tale darkening or burn marks? Then it’s time to test the light socket for incoming voltage.

*Make sure the microwave capacitor is discharged

A quick safety note: If you need to remove the microwave’s cover to reach the cavity light, you should make sure the unit’s capacitor is fully discharged immediately after removing the cover. While most high-voltage capacitors used in recent microwave models have a bleeder resistor in them that should automatically discharge the capacitor after the voltage has been discontinued, it’s always a good idea to confirm this by attempting to discharge the capacitor manually. This can be done by placing a screwdriver blade or needle-nose pliers across each set of capacitor terminals. The handle of the screwdriver or pliers should be insulated, and you should avoid touching the metal portion of the tool when the tool is in contact with the terminals.

How to test a microwave light socket for incoming voltage

Get out your multimeter and follow these 5 steps to test a microwave light socket for incoming voltage:

  1. Set the multimeter’s range selection dial to “Volts AC”.
  2. Plug the microwave’s power cord back into the electrical outlet or restore the power. Since the appliance now has power, you should avoid touching any components with your hands to prevent electrical shock.
  3. If you are testing for voltage reaching the cabinet light, press the light’s “on” button on the control panel to send the potential electrical current to the socket. If you’re testing for voltage reaching the cavity light, you should leave the microwave door open, although be aware that the appliance’s control board may shut off the voltage to the circuit after a few minutes.
  4. Now contact the multimeter’s black and red leads to the light socket power supply wire terminals or pins.
  5. Observe the multimeter display. If the display indicates that voltage is present (readings between 30 and 40 volts are common for most microwave light sockets), the light socket is receiving power. This means that the socket, or the light bulb or light board, is faulty and will need to be replaced. However, if the meter display indicates that no voltage is present, then the cause of the light not working is probably due to a defective main control board unable to provide voltage to the socket. A new main control board will need to be installed to resolve the issue.
Microwave Light Socket Voltage Testing

Choose genuine OEM parts when fixing your microwave

Has your testing determined the light socket needs to be replaced or, maybe, the main control board? Then you’re going to need to purchase the exact matching replacement part that works with your microwave. Repair Clinic recommends using only genuine original equipment manufacturer (OEM) parts that are specifically designed for your microwave model. Where can you find these parts? Just enter the full model number of the microwave in the Repair Clinic website search bar to view a comprehensive list of compatible parts, including those that fit microwaves manufactured by GE, Samsung, Whirlpool, LG, Kenmore, Frigidaire, and Panasonic. You can then use the “Part Category” filter (“Lighting & Light Bulb”) along with the “Part Title” filter (“Light Socket”) to identify the specific part you need.

Free microwave repair help courtesy of Repair Clinic

More than just an extensive parts warehouse, Repair Clinic provides free microwave repair help like the correct way to replace a cavity light socket in a Whirlpool microwave oven/hood combo (model WMH73521CS6), or the best procedure for installing a new main control board on the model FFMV1645TSA Frigidaire microwave. These guides and more can be found in Repair Clinic’s “Videos & Articles” library, an extensive resource for technicians and do-it-yourselfers alike filled with “how-to” videos, step-by-step guides, and product schematics for all major home appliances, lawn and garden equipment, and heating and cooling units.

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