Microwave won’t run: DIY methods to fix it

If your microwave isn’t running, don’t let it get your stomach in a knot. This is a common problem that you can troubleshoot and fix yourself without the need for a costly service call.

If you find out that you need any replacement parts for your microwave while you’re troubleshooting, you can enter your model number at AppliancePartsPros.com to order them. Most orders arrive in just two business days, and we have thousands of free guides to show you how to install your new parts.

Important: The troubleshooting information provided in this article may not apply to your specific appliance model. While we strive to offer helpful advice for DIY appliance repairs, variations in models and configurations can lead to differences in troubleshooting steps, error codes and part replacements. For the most accurate guidance, we strongly recommend consulting the technical sheet for your specific appliance model.

Read more: How to Clean a Microwave  

Safety precautions

Microwaves contain high-voltage parts and have the capacity to store voltage even when they’re disconnected from a power source. Please be very careful while working on a microwave’s internal parts to avoid electrocution, which has the potential to cause serious injuries or death.

• Always power off and unplug your appliance or switch off the circuit breaker before you attempt any maintenance or replacement work. This keeps you safe by eliminating any risk of electric shock.
• Discharge the high-voltage capacitor before working on high-voltage parts to eliminate the risk of electric shock. Don’t continue if you are uncomfortable or unfamiliar with this process.
• Never attempt to run the microwave while its casing is open or when internal parts are exposed. Always completely reassemble the microwave before testing or using it.
• Never attempt to bypass any microwave safety features.
• Never run the microwave empty. Use a glass of water or a bowl of food for testing.
• Removing a microwave from over the range is a two-person job due to the weight and potential for damage. Always follow manufacturer installation instructions to reinstall the unit over the range after repairs have been made.
• If the appliance has recently been used, give it plenty of time to cool down before working on it.
• Take your time while working to prevent accidents and personal injuries. Rushing is the enemy of precision.
• Work in a well-lit area so you can see and access appliance parts.
• Keep your workspace free of clutter and other obstacles. Keep children and pets away from the work area.
• Never work on internal parts with wet hands. Make sure the work area is completely dry.
• Check the user manual to see if there are specific installation or safety instructions related to your appliance or replacement part.
• Be gentle when handling or removing parts. Excessive force might damage the appliance or cause personal injury.
• Wear insulated work gloves to protect your hands from sharp metal parts and debris.
• When working with wires, avoid touching any exposed wires or terminals. If you need to touch a wire, use a non-conductive tool or wear insulating gloves to prevent electrical shock.
• Always take photos or make a note of wiring terminals or other connections before disconnecting them to make reassembly easier.
• Don’t test live voltage with a multimeter if you’re unfamiliar with how to prevent short-circuiting.
• Consider wearing safety glasses and/or a dust mask when working with chemicals, dust or a large amount of debris to prevent irritation or injury.

Read more: How to Install and Replace a Microwave

How to troubleshoot your microwave

Follow these steps to fix a microwave that won’t run.

Step 1: Discharge the microwave’s capacitor 

IMPORTANT: Carefully follow the correct handling and discharge procedures since exposure to the voltage levels inside a microwave can potentially cause severe injury or death. Prioritize safety at all times and follow the instructions and recommendations provided by the manufacturer. If you don’t feel comfortable discharging a capacitor, don’t attempt to do it yourself.

1. Unplug the microwave from the power source.
2. Grab a screwdriver with good insulation on the handle to protect against electric shock.
3. Gently touch the insulated screwdriver blade to one terminal of the capacitor.
4. Slowly and gently slide the screwdriver forward until it reaches the other terminal of the capacitor. Hold it there for a few seconds. This discharge process often results in a loud and startling ‘POP’ sound.
5. Repeat the process to create a short circuit between each capacitor terminal. If the capacitor has three terminals, use the same method.

Step 2: Check the power supply

• Make sure the microwave is plugged into a working electrical outlet. Try plugging in a different appliance to test the outlet. If the outlet is faulty, you’ll need to contact a licensed electrician to fix it.
• Inspect the power cord for any visible damage, such as fraying, cracks, or burns. If the cord appears damaged, replace it with a compatible replacement before moving forward with testing.
• Check the circuit breaker that controls the outlet the microwave is plugged into. Reset the breaker if necessary.

LIVE VOLTAGE WARNING: Please be very careful to protect yourself from electric shock, which has the potential to cause serious injuries. Don’t ever test live voltage if you’re uncomfortable using a multimeter.

• Set a multimeter to voltage AC mode. Use the meter probes to test the voltage at the power outlet. The voltage should be within the microwave’s operating range, which you can find in the unit’s user manual. If you get an unacceptable reading from the power outlet, contact a licensed electrician to fix the problem.

Step 3: Check the fuse

Find the fuse in the microwave. It’s usually near the control panel or behind the access panel.

If the fuse is blown, you’ll need to find the correct fuse size and rating for your model so you can replace it. Once you have a new fuse, plug the microwave in and test it.

If the fuse looks good, continue troubleshooting.

Step 4: Test the door interlock switch

1. Open the microwave door and inspect the door interlock switch, which is usually located near the door latch mechanism.
2. Set a multimeter to continuity mode.
3. Use the meter probes to test the switch for continuity. The primary and secondary switches should close the circuit when the door is closed and open the circuit when the door is open. The middle monitor switch will have the opposite results.

If a switch isn’t functioning properly, replace it with a new compatible part.

If the switch is good, move on to the next step.

Step 5: Check the door latch spring

Find the door latch mechanism and examine the spring that helps the latch engage and disengage. See if the spring is damaged, worn, or has lost its tension. If needed, replace the spring with a new one.

If the spring is good and you’ve made it this far without seeing any issues, there’s one more thing you can check.

Step 6: Check the control board

1. Find the control board, which is typically behind the control panel or access panel.
2. Carefully disconnect the control board from the microwave’s wiring harness and remove it.
3. Visually inspect the control board for any signs of damage, such as burned or discolored areas, cracked traces, or loose connections.

If the control board is faulty, replace it.

Read more: A guide to understanding microwave wattage  

More information

Thank you for reading! We hope this guide helped you get your microwave working again.

If you have any other appliance repair needs or projects, don’t hesitate to explore our other troubleshooting guides and videos.

If you need replacement parts or some extra help with ordering them, grab your model number and head over to AppliancePartsPros.com, where you can chat with a pro, read our DIY blog and more.

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