Samsung Microwave Not Heating: Causes and Fix

Samsung Microwave Not Heating Causes and Fix

Fixing your Samsung microwave’s heating problem is easier than you think. Most of the time it’s caused by incorrect settings, which you can easily change by pressing a button or two.

Although rare, component failure can cause your heating problem. In such cases, you must replace the malfunctioning component or hire a professional.

In our guide, we’ll help you understand why your microwave isn’t heating and show you how to fix it. We’ll give you step-by-step instructions so you can confidently troubleshoot the issue.

Let’s get right into it.

Why is your Samsung microwave not heating?

If your Samsung microwave isn’t heating, it’s most likely because Demo mode is on or its settings are incorrect. It can also be because of inadequate ventilation or door issues.

Component failure is also a possibility. If the cooling fan or magnetron is damaged, your microwave will stop heating up.

Why is your Samsung microwave not heating

How to Fix Samsung Microwave That Isn’t Heating

To fix a Samsung microwave that isn’t heating, make sure it’s not in Demo mode and check if the settings are correct. If not, all you have to do is change the settings to resolve the heating issue.

If you have a faulty component, replace it immediately so your microwave can properly function.

Below, we made a list of all the possible causes behind your Samsung microwave’s heating issue and their corresponding solutions. Try any of these fixes before calling a repair service.

CausesSolutions (Easy)
Demo mode is activated.Tap on the Options button on the control panel.

Click the number 6 button (or the corresponding number for Demo mode on your microwave).

Press the number 2 to deactivate Demo mode.
The microwave has inadequate ventilation.Get a tape measure and use it to verify if your microwave has inadequate ventilation space. 

Measure the space to the right, left, above, and behind your microwave.

Maintain at least 10 cm of space on all sides of your microwave and 20 cm of space above it.
The settings are incorrect.Review your microwave settings and adjust them if it’s necessary.
Use the numeric buttons to set an appropriate cooking time.
Press OK if you want to select a power level other than high. Use the Up/Down button to choose the right power level.
Dirt build-up is preventing the door from closing properly.Fill a bowl with a 1:1 mixture of warm water and vinegar.

Dip a sponge or microfiber cloth into the mixture. Then, use it to wipe all edges and sides of your microwave door.

Use a soft-bristled brush to remove the hardened gunk on your door latch.

Try closing the door all the way and test your microwave if it starts heating again.
CausesSolutions (Medium)
The door switch is damaged.Unplug your microwave and open the door.

Remove the top cover of the microwave and set it aside.

Next, remove the control panel to access the door switches. 

Unmount the switch assembly and free the wires from the retaining clips.

Test your door switches to find out which ones are malfunctioning. Press each switch and listen for a clicking sound. 

Push the release tab on the door switch with weak or no clicking sound. Install the new door switch.

Finally, reattach the control panel and top cover of your microwave.
The thermal fuse has blown. Unplug your microwave. Then, unmount the top panel and the control panel.

Locate the thermal fuse. Detach its wires and remove its mounting screw to release it.

Pull out the fuse and use a multimeter to check for continuity. Touch the first probe to one terminal on the fuse and the second probe to the other terminal.

If the multimeter display doesn’t change, your fuse has no continuity.
Install the new thermal fuse. Replace the screw and connect the wires to the new component.

Reattach the control panel and the top cover.
CausesSolutions (Difficult)
The magnetron is malfunctioning.Unplug your microwave. 

Hold the microwave with one hand and carefully detach the mounting screw with the other.

Pull your microwave out of the cabinet and place it on a solid surface. 

Open the bottom panel. Disconnect the wire harness and wires from the twist retainer.

Remove the top cover and set it aside. Locate the high-voltage capacitor and discharge it. 

Detach the wire connector from the magnetron and remove it from the bracket.

Disconnect the thermal protector from the old magnetron and install it on the new magnetron.

Connect the wires to the new magnetron and attach the screws to lock it in place.

Next, reinstall the top and bottom panels.

Plug your microwave in and test your microwave if it heats up.
The microwave diode has burned out.Unplug your microwave and unmount it from the cabinet. 

Remove the screws on your microwave’s top cover. Lay your microwave on its back and remove the bottom panel. 

Put your microwave in an upright position and open its top cover. Look for the capacitor and discharge it again. 

Unmount the diode and disconnect it from the capacitor. 

Install the new diode by connecting it to the terminal in the capacitor.

Reinstall the screw to lock it in place.

Reinstall the top and bottom covers of your microwave.

Plug your microwave in. Turn it on and check if it heats up.
The cooling fan isn’t working.Unplug your microwave.

Remove the screws mounting the microwave to the cabinet while supporting it with your free hand.

Carefully tilt the microwave forward and lift it up to release it from the support brackets.

Pull the microwave out of the cabinet and place it on a solid surface.

Lay your microwave on its back and remove the bottom panel. Don’t forget to remove the wires on the panel.

Put your microwave in an upright position and unmount the top cover.

Locate the capacitor and let it discharge again before touching anything else. 

Use a small flathead screwdriver to pry out the old fan blade. Insert the new cooling fan blade in the shaft.

Check if the power cord is in its bracket. Then, reinstall the top and bottom covers of your microwave.

Plug your microwave in. Turn it on and check if it heats up.

Easy Microwave Repairs

Lucky for you, the most common heating issues in your microwave require minimal repairs. Sometimes, you just have to change the settings or give your microwave a deep clean to resolve the issue.

Demo mode is activated.

If your Samsung microwave isn’t heating, the first thing you need to do is check if Demo mode is on. It is a hidden feature in your microwave.

Set a cooking time and turn on your microwave. If it counts down fast, your microwave is in Demo mode.

Typically, Demo mode is used at the store to showcase all of the microwave’s functions. In this mode, the magnetron, which generates microwave energy that cooks food, is turned off. 

Thus, you can still use all of your microwave’s functions, but it won’t heat your food. If you turn off the Demo mode, your unit should heat up again.

Solution: To deactivate Demo mode on a Samsung microwave, follow these steps:

  • Step 1: Select the Options button or My Settings depending on your Samsung microwave model.
  • Step 2: Click on the number 6 button or the corresponding number for the Demo function on your microwave.
  • Step 3: Press the number 2 to turn off the Demo mode.

The microwave has inadequate ventilation.

Poor ventilation can cause various problems for your microwave. It will either overheat or not heat at all. 

To check if your microwave has enough ventilation space, measure the space to the right, left, above, and behind your unit.

Solution: If poor ventilation is causing your Samsung microwave to stop heating, you have to reinstall your unit properly. Maintain at least 10 cm of space on all sides of your microwave and 20 cm of space above it.

The settings are incorrect.

Your Samsung microwave has a range of functions. It can be overwhelming to navigate, which is why users often confuse one function for the other.

For instance, your microwave’s kitchen timer isn’t a cooking function. It is a stand-alone feature that can help you keep track of your cooking and other tasks while you’re in the kitchen.

The Keep Warm function also can’t cook food. It can only keep your food at an optimum temperature so it stays warm and delicious when you’re ready to eat it.

Solution: If you suspect that your microwave settings are incorrect, follow these steps:

  • Step 1: Review your Samsung microwave settings.
  • Step 2: Determine the optimal cooking stage for your food.

You can set two different cooking stages on your Samsung microwave and specify the cooking time and power level for each stage.

  • Step 3: Press the numeric buttons on the control panel to set a cooking time.

For one-stage cooking, you only need to set the cooking time. Your microwave’s power level will be automatically set to High.

  • Step 4: Press OK if you want to set the power level to a setting other than High.  Then, use the Up/Down button to choose an appropriate power level for cooking your food.

The power level refers to the heating intensity of your microwave. It ranges from 10 (Warm) to 100 (High).

LevelSettingsLevelSettings
10Warm60Simmer
20Low70Medium High
30Defrost80Reheat
40Medium Low90Saute
50Medium100High

Dirt build-up is preventing the door from closing properly.

If you don’t clean your microwave as often as you should, food can harden and keep your door from latching properly. Unfortunately, it also prevents your microwave from heating.

Solution: To clean the dirt build-up on your microwave door, follow these steps:

  • Step 1: Pour a 1:1 mixture of warm water and vinegar into a bowl.
  • Step 2: Dip a sponge or microfiber cloth in the mixture and use it to clean the door. Clean all edges and sides, especially the latch.
  • Step 3: Use a soft-bristled brush to remove the hardened gunk on your door.
  • Step 4: Try closing the door all the way and test your microwave if it starts heating again.

Medium-Level Microwave Repairs

Medium-Level Microwave Repairs

Medium-level repairs will require you to disassemble your microwave to a certain extent. Although you will be handling internal components, you won’t be dealing with the capacitor just yet. 

For these repairs, you can reach the faulty components by opening the control panel of your microwave. Depending on the faulty component, you might have to perform a continuity test.

Tips:

• Use insulated gloves for protection against electrical shocks.
• Don’t touch the capacitor and other unnecessary internal components if you’re performing the repairs.

The door switch is damaged.

Aside from gunk in the door latch, a broken door switch can prevent your microwave from closing all the way. 

The door switch is the locking mechanism in your microwave. If it breaks, it stops your microwave from heating up.

Solution: To replace a Samsung microwave door switch, follow these steps:

  • Step 1: Unplug your microwave and open the door.
  • Step 2: Remove the screws on the top panel of your microwave.
  • Step 3: Grab the panel and move it slightly to the left. Then, lift it and pull it towards you to remove it.
  • Step 4: Unmount the control panel to access the door switches.
  • Step 5: Remove the screws on the switch assembly.
  • Step 6: Free the wires from the retaining clips.
  • Step 7: Press each door switch and listen for a clicking sound. If you hear weak or no sound at all, your door switch is malfunctioning and needs a replacement.
  • Step 8: Push the release tab on the faulty door switch. Next, gently pull it out of the housing.
  • Step 9: Disconnect the wire from the old door switch. 
  • Step 10: Connect the wire to the new door switch.
  • Step 11: Mount the control panel and its screws.
  • Step 12: Reinstall the top cover and secure it in place.
  • Step 13: Plug your microwave back in.

The thermal fuse has blown.

Your Samsung microwave has at least one thermal fuse, which is responsible for protecting its electrical components. Poor ventilation, power surge, or malfunctioning cooling can cause a thermal fuse to malfunction.

If the thermal fuse blows, your microwave will stop heating. The only way to resolve it is to replace the faulty component.

Solution: To replace a blown thermal fuse, follow these steps:

  • Step 1: Unplug your microwave.
  • Step 2: Unmount the screws on the top panel.
  • Step 3: Hold the panel with both hands and move it slightly to the left. To remove it, carefully lift it and pull it towards you.
  • Step 4: Unmount the control panel and locate the thermal fuse.
  • Step 5: Detach the wires from the old thermal fuse and remove the mounting screw to release it.
  • Step 6: Test the old thermal fuse with a multimeter. Touch the first probe to one terminal on the fuse and the second probe to the other terminal.

If the multimeter display doesn’t change, your fuse has no continuity. You must replace the component.

  • Step 7: Install the new thermal fuse. Reinstall the screw and connect the wires to the new component.
  • Step 8: Reattach the control panel.
  • Step 9: Reinstall the top cover.

Difficult Microwave Repairs

Difficult Microwave Repairs

Unlike the rest of the repairs we’ve mentioned so far, difficult-level repairs require insulated tools and gear. You also need to perform extra steps, such as discharging the capacitor and testing the microwave component with a multimeter.

The capacitor can hold charge even when the microwave is unplugged. This is why you need to discharge the component at least overnight before performing the repair.

To discharge a capacitor, you need a 2W resistor rated for 20,000 ohms, insulated pliers, and an insulated screwdriver. 

  • Step 1: Unplug your microwave and unmount it from the cabinet.
  • Step 2: Disconnect the capacitor using insulated pliers.
  • Step 3: Disassemble the capacitor using your insulated screwdriver.
  • Step 4: Grab your resistor and put one probe on a terminal.
  • Step 5: Touch the other probe onto the other terminal.
  • Step 6: Keep holding the probes for a while to discharge the capacitor.
Tips:

• Use insulated gear for extra protection.
• Always discharge a high-voltage capacitor before working on electrical components in your microwave.
• Let the capacitor discharge at least overnight.
• Avoid using the short circuit method to discharge your capacitor. You can end up damaging the terminals on the component.

The magnetron is malfunctioning.

The magnetron is malfunctioning

The cavity magnetron is your microwave’s main component, which is responsible for cooking food. Any damage to the magnetron will prevent your microwave from heating up.

Unfortunately, you can’t repair a magnetron. Once it malfunctions, you need to replace the old component to continue using your microwave.

Solution: First, you have to test the magnetron using a multimeter. If it has continuity, your magnetron has no problem and you should proceed to the next solution in our guide.

However, if it doesn’t have continuity, you must replace the faulty component.

To test the magnetron, follow these steps carefully:

  • Step 1: Unplug your microwave. Then, remove the glass turntable and base.
  • Step 2: Unmount the screws on the cabinet. Make sure to support the microwave with one hand while you’re removing the screws.
  • Step 3: Tilt it towards you and gently lift it up to release it from its support brackets.
  • Step 4: Pull your microwave out of the cabinet and place it on a solid surface.
  • Step 5: Unmount the screws on your microwave’s top cover.
  • Step 6: Carefully lay your microwave on its back to access the bottom panel. Then, remove the mounting screws.
  • Step 7: Open the bottom panel and disconnect the wire harness. Next, remove the wires from the twist retainer.
  • Step 8: Open your microwave’s top cover.
  • Step 9: Locate the high-voltage capacitor and discharge it again. Let it discharge for a few minutes before proceeding to the next step.
  • Step 10: Detach the wire connector from the magnetron and remove it from the bracket.
  • Step 11: Use the continuity setting of your multimeter.
  • Step 12: Connect the multimeter probes to the magnetron terminals. 

You should hear a beep and see two to three ohms of resistance between those terminals. If there’s no continuity, you need to replace the magnetron.

  • Step 13: Touch one probe to the magnetron case and the other to a terminal to test for a short. If it beeps, you have a shorted magnetron, which will also require a replacement.

Now that you know how to test a magnetron, we’ll show you how to replace it if it lacks continuity. 

To replace a malfunctioning magnetron, follow these steps carefully:

  • Step 1: Unplug your microwave, or turn it off at the circuit breaker.
  • Step 2: Unmount the screws on the cabinet and support the microwave with your free hand. Do not let go of the microwave while you’re unmounting it.
  • Step 3: Hold the microwave with both hands and tilt it towards you. Then, carefully lift it up to release it.
  • Step 4: Remove your microwave from its cabinet and set it on a solid surface.
  • Step 5: Remove the screws on the microwave’s cover.
  • Step 6: Lay your microwave on its back to remove the screws on the bottom panel.
  • Step 7: Open the bottom panel and disconnect the wire harness. Next, remove the wires from the twist retainer.
  • Step 8: Open your microwave’s top cover.
  • Step 9: Discharge the capacitor again and wait for a few minutes before proceeding to the next step.
  • Step 10: Unmount the thermal protector from the old magnetron and attach it to the new magnetron.
  • Step 11: Install the new magnetron by connecting it to the wires. Attach the screws to lock it in place.
  • Step 12: Make sure that the power cord is secure in the bracket.
  • Step 13: Reattach the top panel of your microwave. Align the tabs on the side with the frame and secure the panel with screws.
  • Step 14: Reinstall the bottom panel.
  • Step 15: Plug your microwave in.
  • Step 16: Test your microwave if it heats up.

The microwave diode has burned out.

Your microwave diode converts the transformer’s AC output to DC. 

If it is burned out, your magnetron won’t receive enough voltage to emit microwaves. As a result, your Samsung microwave won’t heat up. 

Solution: Test your microwave diode for continuity. If it has continuity, your diode is functioning properly, so you should look for another possible cause for the problem.

A diode that lacks continuity should be replaced immediately. It’s the only way to resolve your microwave’s heating issue.

To test your microwave diode, follow these steps:

  • Step 1: Unplug your microwave.
  • Step 2: Hold up your microwave with one hand and remove the screws on the cabinet with the other.
  • Step 3: Tilt the microwave forward and lift it to detach it from its support brackets. Then, put your microwave on a solid surface.
  • Step 4: Remove the screws on your microwave’s top cover.
  • Step 5: Lay your microwave on its back and remove the mounting screws on the bottom panel.
  • Step 6: Remove the bottom panel. Disconnect the wire harness and the wires from the retainer.
  • Step 7: Put your microwave in an upright position and open its top cover.
  • Step 8: Look for the capacitor and discharge it again. 
  • Step 9: Disconnect the diode from the capacitor using an insulated screwdriver.
  • Step 10: Get a multimeter and a 9V battery to test for continuity.

Touch the red multimeter probe to one terminal on the battery and the other probe to one end of the diode. Then, touch the tip of the diode to the other battery terminal.

  • Step 11: Try reversing the diode. Connect the probe to the other end of the diode and touch the opposite end of the diode to the battery terminal.

Your microwave diode should only have continuity in one direction. If both ends of the diode have no continuity, it needs to be replaced.

The same goes if you detect continuity in both ends of the diode. It means the component is malfunctioning and requires a replacement.

To replace a malfunctioning microwave diode, follow these steps:

  • Step 1: Disconnect your microwave, or turn it off at the circuit breaker.
  • Step 2: Remove the mounting screws on the cabinet. Make sure to support the microwave with one hand while you’re doing this.
  • Step 3: Tilt the microwave forward and lift it up to release it from its support brackets. 
  • Step 4: Place your microwave on a solid surface and remove the screws on the top cover.
  • Step 5: Lay your microwave on its back and remove the mounting screws on the bottom panel.
  • Step 6: Open the bottom panel. Disconnect the wire harness and the wires from the retainer to release the panel.
  • Step 7: Put your microwave in an upright position and remove its top cover.
  • Step 8: Discharge the high-voltage capacitor again. 
  • Step 9: Install the new diode by connecting it to the terminal in the capacitor.
  • Step 10: Secure the new diode with its screw.
  • Step 11: Mount the top cover of your microwave. Align the tabs on the side with the frame and secure the cover with screws.
  • Step 12: Reinstall the bottom panel.
  • Step 13: Plug your microwave in. Turn it on and check if it heats up.

The cooling fan isn’t working.

Typically, you’ll find a cooling fan next to the control panel in a Samsung microwave. It prevents the internal components from overheating. 

If the fan malfunctions, other electrical components may follow, which can then prevent your microwave from functioning properly. 

Thus, you should always check the cooling fan if you have a heating issue. You might have to replace it with other faulty components.

Solution: To replace a cooling fan in a Samsung microwave, follow these steps:

  • Step 1: Disconnect your microwave from its power source.
  • Step 2: Support the microwave with one hand. Then, carefully remove the mounting screws on the cabinet. 
  • Step 3: Tilt and lift the microwave to release it from the support brackets. Pull it out of its cabinet and place it on a solid surface.
  • Step 4: Remove the screws on your microwave’s top cover.
  • Step 5: Lay your microwave on its back and remove the mounting screws on the bottom panel.
  • Step 6: Remove the bottom panel. Disconnect the wire harness and the wires from the retainer.
  • Step 7: Put your microwave in an upright position and open its top cover.
  • Step 8: Look for the capacitor and discharge it again. 
  • Step 9: Locate the old fan blade and use a flathead screwdriver to pry it off.
  • Step 10: Install the new cooling fan blade in the shaft.
  • Step 11: Check if the power cord is in its bracket.
  • Step 12: Reinstall your microwave cover. Align the tabs on the side with the frame and secure the cover with screws.
  • Step 13: Reinstall the bottom panel.
  • Step 14: Plug your microwave in. Turn it on and check if it heats up.

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