Troubleshooting Guide: Why Your LG Microwave Isn’t Heating and Making a Humming Sound

Is your LG microwave not heating up as it should and emitting a perplexing humming sound instead? Fret not, as we have got you covered with this comprehensive troubleshooting guide. A malfunctioning microwave can disrupt your daily routine, but understanding the reasons behind it can help you address the issue effectively.

In this article, we will delve into the common culprits behind an LG microwave failing to heat food properly and the humming noises it may make. By following our step-by-step troubleshooting tips, you will be equipped with the knowledge to diagnose and potentially resolve the issues plaguing your appliance, ensuring it operates at its optimal performance once again.

Key Takeaways
If your LG microwave is not heating and making a humming sound, it could be a sign that the magnetron, which is responsible for producing the microwaves that heat the food, is failing. The humming sound may indicate that the magnetron is receiving power but not functioning properly to heat the food. It is recommended to have a professional technician inspect and repair the magnetron or other internal components to restore the microwave’s functionality.

Check The Power Supply

To troubleshoot why your LG microwave isn’t heating and is making a humming sound, start by checking the power supply. Make sure the microwave is plugged into a functioning power outlet and that the cord is securely connected. If the power outlet is working, but the microwave still isn’t heating, try plugging another device into the same outlet to confirm it is providing power.

Next, check the circuit breaker or fuse box to ensure there are no tripped breakers or blown fuses affecting the power supply to the microwave. Reset any tripped breakers and replace any blown fuses with the appropriate amperage. If the power supply seems to be in order and the microwave still isn’t heating, there may be an issue with the microwave’s internal components that require professional diagnosis and repair.

Regularly checking the power supply of your LG microwave is essential for ensuring it functions properly. By following these troubleshooting steps, you can determine if the power supply is the root cause of the heating issues and humming sound coming from your microwave.

Ensure Proper Placement

To ensure your LG microwave operates efficiently, proper placement is essential. Incorrect placement can hinder its ability to heat food effectively and lead to a humming sound. Start by verifying that your microwave is sitting on a flat, level surface to prevent any vibrations or tilting that can cause noise during operation. Additionally, ensure that there is enough clearance space around the microwave for proper ventilation.

Moreover, distance your microwave from heat sources, such as ovens or stovetops, as the additional heat can affect its performance. Avoid placing the microwave in direct sunlight or near a window to prevent overheating. If the microwave is built-in, check that the ventilation openings are not blocked by cabinetry or other items, as restricted airflow can impact the unit’s heating capabilities.

By following these placement guidelines, you can help troubleshoot why your LG microwave may not be heating properly and is emitting a humming sound. Proper placement ensures optimal performance and enhances the longevity of your appliance.

Examine The Turntable

When troubleshooting your LG microwave for heating issues and a humming sound, examining the turntable is essential. The turntable rotates the food to ensure even cooking by exposing it to the microwave’s energy from different angles. If the turntable is not functioning correctly, this can lead to uneven heating or no heating at all.

To examine the turntable, remove it from the microwave and inspect it for any signs of damage or obstruction. Check the turntable support to see if it is properly aligned and functioning smoothly. Sometimes, food particles or grease buildup can cause the turntable to get stuck or not rotate properly, leading to heating issues.

If you find any issues with the turntable, clean it thoroughly and ensure it is correctly positioned back into the microwave. If the turntable appears to be damaged, it may need to be replaced to restore proper functioning. Proper maintenance of the turntable is crucial for optimal microwave performance and to avoid heating problems and humming sounds.

Inspect The Door And Door Switches

Inspect the door and door switches to ensure they are functioning properly. Begin by checking if the door is closing firmly and securely. A loose or misaligned door may prevent the microwave from heating properly. Additionally, examine the door switches to see if they are intact and not damaged. The door switches are crucial for the microwave to operate safely and efficiently.

If the door and door switches appear to be in good condition, try opening and closing the door a few times to listen for any unusual clicking or rattling sounds. These sounds may indicate a problem with the door mechanism that could be affecting the microwave’s heating ability. Make sure there are no obstructions hindering the door’s closing, such as food debris or objects blocking the seal.

Lastly, clean the door and the surrounding areas to remove any dirt or grease buildup that could be interfering with the door’s proper operation. Regular maintenance of the door and door switches can help prevent issues with your LG microwave and ensure it continues to heat your food effectively without making a humming sound.

Test The Magnetron

To test the magnetron in your LG microwave, you will need a multimeter. Start by unplugging the microwave and removing the cabinet to access the magnetron. Locate the magnetron, which is a cylindrical device typically found near the microwave’s heat source.

Once you have located the magnetron, carefully discharge the high-voltage capacitor to ensure safety. Use the multimeter to measure the resistance across the magnetron’s terminals. A functioning magnetron should typically have a resistance reading within a specific range (refer to the microwave’s manual for the exact values).

If the resistance reading is significantly higher or lower than the expected range, it indicates a faulty magnetron that needs to be replaced. Additionally, if there is no resistance reading at all, this also points to a malfunctioning magnetron. Keep in mind that testing the magnetron should only be done if you have experience with electrical components and understand the risks involved.

Evaluate The High Voltage Diode

To evaluate the high voltage diode in your LG microwave, start by ensuring the appliance is unplugged and safe to work on. The high voltage diode plays a crucial role in allowing the microwave to generate heat, so it is essential to check its condition if your microwave is not heating properly. Visually inspect the diode for any signs of burning, cracking, or damage. If you notice any physical defects, it is likely that the diode needs to be replaced.

You can also test the high voltage diode using a multimeter to check for continuity. A functioning diode should allow electrical current to flow in one direction but not the other. If the diode shows no continuity, it is defective and needs to be replaced. However, if the diode tests fine, then the issue may lie elsewhere in the microwave’s circuitry. By evaluating the high voltage diode, you can troubleshoot one of the common reasons why your LG microwave is not heating and making a humming sound.

Clean The Interior

To address the issue of your LG microwave not heating and making a humming sound, cleaning the interior is a crucial step in troubleshooting. Food particles and debris can accumulate inside the microwave over time, affecting its performance. Before cleaning the interior, ensure the microwave is unplugged for safety purposes.

Start by removing the glass turntable and any other detachable parts. Wash these components in warm, soapy water and dry them thoroughly before placing them back inside the microwave. Using a mixture of water and mild detergent, wipe down the interior walls and ceiling of the microwave with a soft cloth or sponge. Pay close attention to the areas around the waveguide cover and stirrer fan, as these can also collect grease and grime.

After cleaning the interior, let the microwave air dry for a few hours to ensure all moisture has evaporated before plugging it back in. Regularly cleaning the interior of your LG microwave can help prevent overheating issues and maintain its optimal performance.

Consult A Professional

If you have attempted all the troubleshooting steps mentioned and your LG microwave still isn’t heating and continues to make a humming sound, it may be time to consult a professional. A certified technician will have the knowledge and expertise to diagnose and repair more complex issues with your microwave.

Attempting to repair electrical appliances without the necessary skills and training can be dangerous and may cause further damage. A professional technician will be able to accurately identify the root cause of the problem and provide a safe and effective solution to get your LG microwave back in working order.

By seeking help from a professional, you can ensure that your microwave is repaired correctly, avoiding any potential safety hazards and extending the lifespan of your appliance. Don’t hesitate to reach out to a qualified technician for assistance with troubleshooting and repairing your LG microwave.


What Are Common Reasons For An Lg Microwave Not Heating Up?

Common reasons for an LG microwave not heating up include a faulty magnetron, a defective high voltage diode, a malfunctioning capacitor, or a broken door switch. If any of these components are not functioning properly, the microwave will not be able to generate the necessary heat to cook food. Another possible cause could be an issue with the thermal fuse, which may disrupt the microwave’s heating capabilities. Troubleshooting these components and seeking professional repair may be necessary to resolve the heating problem in an LG microwave.

Why Is My Lg Microwave Making A Humming Sound?

A humming sound from your LG microwave could indicate a problem with the turntable motor or the cooling fan. These components may be malfunctioning or experiencing some sort of obstruction, causing the humming noise. It is recommended to unplug the microwave and check for any visible obstructions or damage to these parts before seeking professional help for repair.

How Can I Troubleshoot An Lg Microwave That Is Not Heating?

If your LG microwave is not heating, try resetting it by unplugging it for a few minutes and then plugging it back in. Make sure the door is properly closed and the timer is set correctly. If the issue persists, check if the turntable is rotating smoothly and inspect the internal components for any signs of damage. If you are unable to resolve the problem on your own, contact LG customer service for further assistance or consider bringing the microwave to a professional technician for repair.

What Should I Do If My Lg Microwave Is Making Unusual Noises While In Operation?

If your LG microwave is making unusual noises while in operation, it is best to stop using it immediately for safety reasons. Unusual noises could be a sign of an internal issue or malfunction that needs to be addressed by a professional technician. Contact LG customer service or a certified appliance repair service to schedule a diagnostic appointment and repair if necessary. Continuing to use a microwave that is making strange noises could potentially lead to further damage or even pose a safety risk, so it’s important to address the issue promptly.

Are There Any Simple Fixes I Can Try Before Calling For Professional Assistance With My Lg Microwave?

Before calling a professional for your LG microwave, try simple fixes like cleaning the interior and exterior, checking the power source, and resetting the circuit breaker. Ensure the microwave is on a stable surface and that the door is properly closed. In case of error codes, consult the manual for troubleshooting tips. If these steps don’t resolve the issue, it may be time to seek professional assistance to diagnose and repair any underlying problems.


In understanding why your LG microwave is not heating and emitting a humming sound, it is crucial to systematically troubleshoot the issue to pinpoint the exact cause. By following the step-by-step guide outlined in this article, you can identify common problems such as a faulty magnetron, diode, or capacitor. Additionally, checking power supply issues and ensuring proper ventilation can significantly impact the microwave’s functionality.

Taking a proactive approach to addressing these concerns can not only save you time and money on costly repairs or replacements but also enhance the performance and longevity of your LG microwave. By regularly maintaining and diagnosing any issues promptly, you can enjoy the convenience and efficiency that your microwave is designed to provide.

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