Skip to Content

Samsung Microwave Not Heating? Here’s Why (+ How To Fix)

A Samsung microwave not heating is a common issue because it has a lot of critical components that can fail over time or suddenly. Also, its customizable settings or functions can cause some errors. So, why is your Samsung microwave, not heating, and how do you fix it? 

In this article, I’ll investigate why your Samsung microwave fails to heat your food. Most importantly, I’ll show you how to fix it. So, there is no need to call a technician just yet! 

With my easy-to-follow steps and practical tips, your microwave will be up and running quickly. Let’s get cooking again and bid farewell to those disappointing lukewarm meals!

Quick Reasons Your Microwave Will Not Heat

Don’t have enough time to read the whole article? Here is a quick rundown of the possible reasons causing the microwave to leave your meals cold:

  • The microwave is stuck in demonstration mode.
  • The door fails to close or secure properly.
  • One of the door switches is malfunctioning.
  • The settings lack precision or accuracy.
  • Insufficient or restricted ventilation affects performance.
  • The cooling fan fails to operate.
  • There is a blown internal thermal fuse.
  • The thermoprotector is damaged.
  • A faulty high-voltage diode affects functionality.
  • The microwave capacitor is defective.
  • The oven transformer has ceased to function.
  • The magnetron is not operating correctly.
  • A defective control board hinders performance.
  • The unit experiences electrical complications.

I assume you need more detailed information now that you are still here. Without further ado, let’s jump into more detail about these problems and how to fix them:

The Microwave Is Stuck In Demonstration Mode:
When the Samsung microwave gets stuck in demonstration mode, it operates for display purposes rather than regular cooking. 

How to fix:

  • Locate the “Settings” or “Options” button on the control panel.
  • Press the button to access the microwave’s settings menu.
  • Look for an option related to demo mode and select it.
  • Follow the on-screen prompts to turn off the demo mode.
  • Once done, exit the settings menu and test the microwave to ensure it’s functioning normally.

Following these steps, you can turn off the demonstration mode on your Samsung microwave and resume regular cooking operations.

The Door Fails To Close Or Secure Properly

When the door of a Samsung microwave fails to close or lock properly, it can result in a microwave that doesn’t heat. The door latch activates the internal circuit, which powers the magnetron to generate the microwaves necessary for heating. 

If the door doesn’t close or lock correctly, it can be due to accumulated dirt, a broken door latch or spring, or misalignment or deformation of the door.

How to fix:

To address this issue, follow these steps:

  • Thoroughly clean the door to remove any dirt or debris.
  • Check the functionality of the door latches.
  • Replace any broken door latches or springs.
  • Properly level the Samsung microwave. 
  • Inspect and correct any misalignment or deformation issues with the door.

Malfunctioning Door Switches 

The door latches in a Samsung microwave serve as the mechanism for locking and triggering, but they are not responsible for activating or deactivating the electrical circuit inside the appliance. 

Inside the microwave, separate door switches can break, causing the microwave to lose its heating function. Most Samsung microwaves have a minimum of two-door switches, though some models may have more. 

These switches are independent of the control panel and display, allowing you to interact with the microwave and adjust settings. However, if one of these switches is defective, the microwave will not generate heat.

How to fix:

  • Disconnect the Samsung microwave from the power outlet.
  • Gather a Phillips and Torx screwdriver and a multimeter or continuity tester.
  • Remove the screws securing the control panel section, including those on the top, front, and sides.
  • Open the housing panel to access the door switches.
  • Take a photo of the wires and connectors for future reference.
  • Unplug the wire harnesses and remove the faulty door switches.
  • Set the multimeter to continuity or the least resistance setting.
  • Place the probes on the terminals of each door switch.
  • Press the door switch actuator and check the reading. A functioning switch will produce a sound or illuminate an LED if using a continuity tester.
  • Replace any door switch that shows no continuity or resistance.

Settings Lack Precision Or Accuracy:

Samsung microwaves offer a range of customizable settings, but sometimes these settings may not work together harmoniously. Consequently, the microwave doesn’t heat up.

To troubleshoot this issue, check if any selected settings interfere with the heating function. Pay attention to the following settings:

  • Kitchen timer: This setting is not meant for cooking or microwaving but instead serves as a timer or alarm function.
  • Keep warm: The “keep warm” mode does not heat food; it simply maintains a warm temperature.
  • Power level: The selected power level determines the heating intensity. Samsung microwaves typically offer power levels such as warm, low, defrost, medium-low, medium, simmer, medium-high, reheat, sauté, and high.

Additionally, be aware that overstuffing the microwave or using incompatible containers and cookware can affect the microwave’s heating performance, causing uneven or inadequate heating.

How to fix:

  • Choose a cooking cycle instead of relying on the kitchen timer.
  • Avoid using the “keep warm” mode if you require heating.
  • Select the appropriate power level that suits your heating needs.
  • Ensure the microwave is not overstuffed, allowing proper heat circulation.
  • Use microwave-safe containers and cookware compatible with your Samsung microwave.

Insufficient Or Restricted Ventilation

Proper ventilation is crucial for the effective and efficient operation of Samsung microwaves. The microwave may not heat appropriately without adequate ventilation and can trigger a cooling-related shutdown mechanism. 

It is essential to provide sufficient clearance around the microwave to prevent overheating, a common cause of blown thermal fuses and thermistors.

Overheating can also lead to charring or burning specific components, often caused by power surges. Therefore, ensuring your Samsung microwave is well-ventilated and properly installed is important.

In addition to ensuring proper clearance around the microwave, it is important to check the functionality of the blower. Even if there is sufficient space and clear vents, a malfunctioning blower can impede proper ventilation and affect the microwave’s performance.

By double-checking the installation, ensuring adequate ventilation, and verifying the proper functioning of the blower, you can address potential issues that may prevent your Samsung microwave from heating effectively.

How to fix:

  • Ensure adequate space: To address this issue, ensure adequate clearance around the microwave, following manufacturer guidelines. Samsung has different clearance distances for various models per size and capacity.
  • Clean vents: Overheating, often caused by blocked vents or insufficient space, can lead to blown thermal fuses and damaged components. Regularly clean the vents to maintain optimal airflow. Additionally, check the blower’s functionality to ensure proper ventilation. 

If the blower isn’t running or airflow is reduced, seek professional assistance. Maintaining proper ventilation enhances microwave performance and prevents overheating problems.

Cooling Fan Fails To Operate

In Samsung microwaves, a cooling fan is located near the control panel, which is crucial in protecting electronic components. It operates quietly and resembles the fans used in desktop computers. If this fan fails to operate, it can result in the microwave not heating properly.

To address this issue, it may be necessary to disassemble the microwave and investigate potential problems. 

However, a malfunctioning cooling fan may not be the sole cause of the heating problem. Other electrical components and sensors within the microwave could also contribute to the issue.

How to fix:

  • Access the cooling fan: You must disassemble the microwave to access the fan. Refer to the specific user manual for your model or seek online resources that provide instructions on safely accessing the internal components.
  • Visually inspect: Once you have gained access to the cooling fan, inspect it for any visible damage, such as loose wires, broken blades, or accumulated dirt and debris. 
  • Check the wirings: Clean the fan blades using a soft brush or compressed air to remove any dust or obstructions hindering their operation. Next, check the wiring connections of the cooling fan to ensure they are securely attached. If you notice any loose or damaged wires, carefully reattach or replace them following proper electrical safety precautions.
  • Manually rotate the cooling fan while the microwave is unplugged to ensure smooth movement. If the fan feels stiff or does not rotate, it is likely faulty, and you need to replace it. 
  • Replace the fan: Obtain a suitable replacement from a Samsung authorized service center or a reputable electronics store. Follow the manufacturer’s instructions or seek professional assistance to install the new cooling fan safely.
  • Reassemble: After completing the repairs or replacement, reassemble the microwave, ensuring all components are securely in place. Plug the microwave back into the power source and run a test heating cycle to verify that the cooling fan is operating correctly.

Blown Internal Thermal Fuse

In Samsung microwaves, there is a crucial component called the thermal fuse, responsible for safeguarding the control board and electronic elements, including the sensors. When the thermal fuse blows, it prevents the microwave from heating.

Several factors can cause a thermal fuse to blow, including power surges, overheating, or the presence of a faulty part.

However, it is important to note that the overheating issue can stem from various sources, such as inadequate ventilation, a malfunctioning blower, or a defective cooling fan. Hence, don’t just focus on inspecting and fixing the thermal fuse alone. Take it further and conduct a thorough investigation to uncover any other damaged components. 

By delving into a comprehensive examination, you can pinpoint the exact issues and craft a tailored solution that guarantees a successful repair. Don’t settle for a quick fix; strive for a lasting resolution.

How to fix:

  • Unplug the microwave and proceed with the disassembly process described earlier in the section on door switches.
  • Once you have removed the front control panel section, locate the thermal fuse within the microwave.
  • Carefully remove the thermal fuse from its position and perform a continuity test using a multimeter or tester. A properly functioning thermal fuse should exhibit continuity, indicating minimal resistance. The resistance reading should be close to 0 ohms but not be open-loop or show infinite resistance.
  • If the thermal fuse fails the continuity test, replace it with a new one specifically designed for your Samsung microwave model.

A Damaged Thermo-Protector

Samsung microwaves have thermoprotectors that play a vital role in the heating system. If the main thermoprotector fails, the entire heating mechanism becomes non-functional. 

It’s important to understand that thermoprotectors differ from thermal fuses as they function as thermistors or thermostats.

Thermal fuses can blow out due to abnormal electricity or heat and need replacement. Thermoprotectors reset themselves after interrupting the electrical circuit during overheating and automatically restore functionality when the unit cools down.

However, if the thermoprotector is defective, it will prevent the microwave from activating when you set it to heat. The main thermoprotector keeps the circuit open, preventing electricity from reaching the heating system.

Likewise, a malfunctioning cooling fan thermoprotector fails to regulate the temperature of the electronics, potentially leading to overheating. This, in turn, can result in a blown thermal fuse. Alternatively, the main thermoprotector may interrupt the heat supply to protect the microwave from potential damage.

Therefore, when encountering heating issues with your microwave, it is crucial to assess the condition of the thermoprotectors and ensure they are functioning correctly.

How to fix:

  • Disconnect: First, ensure the microwave is safely disconnected from the power source. 
  • Dismantle: Proceed by carefully dismantling the microwave to gain access to its internal components, including the thermoprotector. Identify the main thermoprotector responsible for the malfunction by looking for any visible signs of damage, such as cracks or discoloration. If it appears to be faulty, you will need to replace it.
  • Get a thermoprotector: Obtain a suitable replacement thermoprotector compatible with your Samsung microwave model. You can find this component at authorized service centers or reputable stores specializing in appliance parts. Once you have the replacement, install it securely in the designated position within the microwave, ensuring proper alignment.
  • Reassemble: Next, reassemble the microwave by replacing the panels or covers you removed and fasten them in place. Once the reassembly is complete, reconnect the microwave to the power source.

To test it, adjust the microwave to the desired heat settings. If the replacement of the thermoprotector replacement was successful, the microwave should now be able to heat your food. 

A Faulty High-Voltage Diode

The high-voltage diode is a crucial component in Samsung microwaves and is connected to the capacitor. Its primary function is to amplify the voltage received from the transformer. Additionally, the high-voltage diode is crucial in converting AC to DC, essential for the magnetron to operate effectively.

However, if the high-voltage diode malfunctions or becomes defective, it will prevent the magnetron from receiving the high voltage required to generate microwaves. Consequently, your Samsung microwave will fail to produce the desired heating effect.

How to fix:

To determine if the high-voltage diode in your Samsung microwave is faulty, you can perform a continuity test. However, ensuring your safety by using insulated gear and allowing the microwave capacitor to discharge overnight before attempting any tests is crucial.

Here is a simplified procedure to test the high-voltage diode:

  • Safely disconnect the high-voltage diode from the capacitor using insulated pliers.
  • Use a multimeter with a 9V battery (not a simple continuity tester) for accurate results.
  • Test the continuity by placing the multimeter probes on the diode’s terminals.
  • The multimeter should indicate continuity when the probes are connected in one direction, confirming a suitable diode.
  • Reversing the probes should result in no continuity.
  • The diode is faulty if there is continuity in both directions or no continuity in either direction.

Defective Microwave Capacitor

A faulty high-voltage capacitor is often responsible for a Samsung microwave’s failure to heat. It is important to exercise caution and ensure you have fully charged the capacitor before attempting to access it. Discharging high-voltage capacitors requires different methods compared to low-voltage capacitors.

If there are no visible indications of damage, it may be necessary to test the high-voltage capacitor to determine if it is faulty.

How to fix:

For the safe discharge of a high-voltage capacitor in a Samsung microwave, it is advisable to let it discharge slowly over a long duration, preferably overnight or for an extended period. Another method is to use a 2W resistor with a rating of 20,000 ohms.

Follow these steps to discharge the high-voltage capacitor:

  • Unplug the microwave and carefully dismantle the housing.
  • Use insulated pliers to disconnect the wires connected to the capacitor.
  • Use an insulated screwdriver to disassemble the capacitor.
  • Take one probe of the 2W, 20K ohms resistor and place it on one terminal of the capacitor.
  • Use the second probe of the resistor to touch the other terminal.
  • Hold the probes in place to allow the capacitor to discharge.
  • Some high-voltage capacitors may have three terminals. In such cases, start using one probe on the outer terminal and the other on the center terminal. Then, cover the remaining external terminals, ending with the other central terminal.

Avoid using a screwdriver to connect multiple terminals for discharging the high-voltage capacitor. Also, refrain from using the short circuit method typically employed for low-voltage capacitors, as it may cause damage to the terminals of the capacitor in your Samsung microwave.

Using a regular multimeter or other methods is unsafe for discharging high-voltage capacitors. After discharging the high-voltage capacitor, you can test it using a multimeter:

  • Check the resistance of the capacitor by placing the multimeter probes on its terminals.
  • Set the multimeter’s resistance setting accordingly.
  • The reading should be around the rated resistance of the capacitor.
  • If you use an analog multimeter, observe any deviation in the reading.
  • Place the probes on the terminals and note any jump or spike in the reading.
  • Reverse the probes or terminals and observe any changes in the reading.
  • If there is no spike or reading, it indicates a faulty capacitor.
  • A suitable capacitor should only have continuity if it is shorted. Therefore, a continuity test does not help test a capacitor. However, you can still perform a continuity test to identify a faulty or shorted capacitor by using one probe on a terminal and the other on the capacitor’s chassis.
  • If you detect a faulty or shorted high-voltage capacitor, you should replace it.

Non-functional Oven Transformer

Visible signs of damage such as deformation, arcing, or burnt windings can indicate a blown transformer in a Samsung microwave. However, it is important to note that other internal issues could also be responsible for the problem.

How to fix:

  • Replace: To fix the problem of a blown transformer in a Samsung microwave, you must replace the damaged transformer. Start by unplugging the microwave from the power source. 
  • Disassemble: Disassemble the microwave following appropriate instructions or seek professional guidance to access the blown transformer. Take note of the specific model and specifications of the existing transformer to ensure you purchase the correct replacement.
  • Disconnect: Once you have acquired the new transformer that matches the required specifications, carefully disconnect the old transformer, noting the wire positions for proper reinstallation. Take caution and ensure your safety by wearing appropriate protective gear.
  • Install: Install the new transformer in the same location, ensuring secure wire connections based on the previous positions. Handle the components carefully to avoid further damage. 
  • Reassemble: After securely installing the new transformer, reassemble the microwave by following the reverse steps of the disassembly process. Double-check that you have correctly secured all connections before plugging the microwave into the power source.

To confirm if the issue has been resolved, perform a test run of the microwave.

Faulty Magnetron

The internal mechanism of the microwave relies on the magnetron to generate and release the microwaves. 

After examining all the mentioned components and issues, if the microwave turns on but doesn’t heat, it is likely due to a faulty magnetron or a malfunctioning control board. 

However, if the control panel, buttons, and settings are operational, conducting a thorough test targeting the magnetron is essential.

How to fix:

Unplug the microwave and discharge the capacitor to ensure safety, as explained earlier.

  • Remove the magnetron from the microwave.
  • Take a multimeter and set it to the lowest resistance setting.
  • Touch the terminals of the magnetron with the multimeter probes. The multimeter should show a normal resistance reading. The magnetron is not functioning correctly if it shows no or infinite resistance.
  • Change the multimeter to the highest resistance setting.
  • Connect one probe of the multimeter to either magnetron terminal.
  • Place the other probe on the magnetron’s case. If the multimeter displays a reading, it indicates a shorted magnetron.
  • You can also use a continuity test to check for a short. There should be no continuity between any terminal and the magnetron case.
  • If the magnetron is shorted, it is defective and requires replacement.

A Defective Control Board:

If you are still encountering the same issue after trying the solutions mentioned above. You need to follow this diagnosis and repair method:

How to fix:

  • Reset the control board: Unplug the microwave from the power source and wait a few minutes before plugging it back in. This can help fix any temporary glitches or software problems.
  • Check: Make sure all the wires are securely attached between the control board and other microwave parts. Loose connections can lead to malfunctions and affect the microwave’s performance.
  • Replace faulty components: If you identify specific faulty components on the control board, like damaged capacitors or resistors, you may need to replace them. Consult the user manual or seek help from a professional to find suitable replacements and properly install them.

If the previous steps don’t solve the issue, it’s best to seek professional repair services. Contact Samsung customer support or a trusted appliance repair technician who can diagnose the problem and provide a suitable solution.

In some cases, if the control board is severely damaged and cannot be fixed, it may need to be replaced entirely. Contact Samsung or an authorized service center to inquire about obtaining a compatible replacement control board.

Prioritize safety by unplugging the microwave before attempting any repairs. If you’re unsure or uncomfortable fixing it yourself, it’s better to rely on professional help to ensure a safe and effective solution.

Electrical Complications

A variety of electrical problems can cause your Samsung microwave to stop heating. Possible reasons for this issue include voltage fluctuations, amperage problems, incompatible wiring, a defective power cable, inappropriate use of a surge protector or extension cord, electrical shorts, and broken wires.

How to fix:

  • Check voltage fluctuations: First, check for voltage fluctuations in the power supply. Make sure the voltage remains stable without sudden changes. If you notice fluctuations, consider using a voltage stabilizer or consult an electrician to address the issue.
  • Ensure: Next, ensure that the electrical circuit can provide sufficient amperage for the microwave. If the amperage is too low, you may need to upgrade the circuit or use a separate circuit dedicated to the microwave. Contact an electrician for assistance with this.
  • Check wiring: This helps to determine if the wiring in the microwave is compatible with the electrical system and outlet. Incompatible or faulty wiring can prevent proper heating. Consult an electrician to replace or repair the wiring to ensure compatibility.
  • Inspect: Inspect the power cable of the microwave for any damage or wear. A damaged cable can disrupt the flow of electricity and hinder heating. Replace the power cable with a new one that matches the specifications of the microwave.

Avoid using surge protectors or extension cords for the microwave. It is best to plug the microwave directly into a wall outlet to ensure a stable power supply and improve heating performance.

If you suspect an electrical short inside the microwave, it’s essential to seek professional help. Contact a qualified technician to inspect and repair any electrical shorts. Attempting to fix electrical shorts yourself can be unsafe.

Finally, if there are any broken or damaged wires inside the microwave, it’s crucial to have them repaired or replaced by a professional technician. Contact a qualified technician to address the issue and ensure proper heating functionality.


If your Samsung microwave turns on but doesn’t heat, several potential causes and solutions exist. 

We’ve covered everything from being stuck in demonstration mode to issues with the door, door switches, settings, ventilation, cooling fan, internal components like the thermal fuse and thermoprotector, and high-voltage components like the diode and capacitor. 

You can fix many problems without a technician by following the troubleshooting steps and tips. So, don’t let lukewarm meals disappoint you any longer; let’s get your microwave back to its heating glory!


What are the possible reasons why my microwave doesn’t heat?

Possible reasons why a microwave doesn’t heat can include a faulty magnetron, a malfunctioning high-voltage capacitor, a defective diode, a faulty door switch, or a problem with the control board.

How can I troubleshoot a microwave that doesn’t heat?

To troubleshoot a microwave that doesn’t heat, you can start by checking if the power supply is functioning correctly, ensuring the door is closing properly, examining the control settings, and testing the components like the magnetron, capacitor, diode, and door switches.

How much does it cost to repair a microwave that doesn’t heat?

The cost of repairing a microwave that doesn’t heat can vary depending on the specific issue, the model of the microwave, and the service provider. I recommend that you consult a professional technician who can diagnose the problem and estimate the repair costs.


  • Chris Hewitt

    Chris is a Texas-based freelance writer who loves the outdoors and working in his garage. When he's not enjoying the Texas sun, he can be found tinkering with all sorts of things in his workshop.

As an Amazon Associate, we earn from qualifying purchases. We may also earn commissions if you purchase products from other retailers after clicking on a link from our site.