Kenmore Microwave Not Heating? 6 Easy DIY Fixes!

Owning a Kenmore microwave is a convenient way to simplify your kitchen routine. However, it can be frustrating when your microwave runs without heating your food.

If you’re facing the dilemma of a Kenmore microwave not heating but running, you’re not alone.

We will walk you through troubleshooting Kenmore microwave issues and fixing common problems that prevent your microwave from heating.

Troubleshooting Kenmore Microwave Not Heating?

Common reasons your Kenmore microwave won’t heat food include a faulty high-voltage diode, defective door switch, blown fuse, capacitor malfunction, faulty Thermo protector, and a burnt-out magnetron.

Kenmore Microwave Not Heating

Now, let’s start fixing these issues.

1. Faulty High Voltage Diode

A functioning high-voltage diode is critical for your Kenmore microwave to heat food efficiently.

When this component becomes defective, your microwave may continue to run but won’t heat your food.

The diode’s role in the microwave is to convert electrical currents; if it fails, the heating process is disrupted.

How to Fix:

First and foremost, ensure your safety by unplugging the microwave. High-voltage components carry risks and require careful handling.

Once you ensure safety, locate the diode connected to the high-voltage capacitor.

Inspect it for any visible signs of damage. The next step involves using a multimeter to test the diode.

Proper functioning diodes will show infinite resistance in one direction and no resistance in the opposite. If your test results differ, the diode needs replacing.

For those with experience in microwave repairs, replacing the diode is the next step.

However, you should seek professional assistance if you lack confidence in your repair skills.

2. Defective Door Switch

The door switch plays a vital role in the safety and functionality of the microwave. It ensures that the microwave operates only when the door is securely closed.

If the door switch is malfunctioning, it could be why your microwave isn’t heating.

How to Fix:

To address this issue, start by accessing the switch. You’ll need to open the front panel of the microwave to locate the door switches.

Once accessible, the next step is to test each switch for continuity using a multimeter.

This test will help you determine if the switch is functioning correctly or not.

A lack of continuity in any switch indicates a problem that requires attention. If a switch is found to be faulty, it should be replaced.

3. Blown Fuse

A blown fuse is a common issue in Kenmore microwaves and can be the culprit behind the microwave’s heating problem.

Fuses act as a safety mechanism to prevent electrical overload. When they blow, the microwave ceases to function entirely, including the heating element.

Repairing Kenmore microwave not heating

How to Fix:

Start fixing the Kenmore microwave not heating by unplugging and locating the fuse, typically found near the microwave’s power cord.

Carefully remove the fuse and test it with a multimeter for continuity.

A blown fuse will show no continuity and needs replacement. When selecting a new fuse, ensure it matches the specifications of the original one, including the same amperage and voltage ratings.

Replace the fuse and secure all components back in place.

After replacing the fuse, plug the microwave back in and test it. If the microwave starts heating again, the problem is resolved.

4. Capacitor Malfunction

A malfunctioning capacitor can disrupt this process, leading to issues with your microwave’s ability to heat.

How to Fix:

Locate the capacitor, which is usually situated near the high-voltage diode.

Before proceeding, it’s critical to discharge the capacitor to avoid any risk of electrical shock.

Use a screwdriver with an insulated handle to bridge the capacitor’s terminals, safely discharging any stored energy.

Once discharged, test the capacitor with a multimeter set to the capacitance measurement mode.

If the readings are significantly off from the capacitor’s rated capacitance, it’s time for a replacement.

Carefully remove the old capacitor, note how it’s connected, and replace it with a new one that matches the original specifications.

After replacement, reassemble and test your microwave to see if the heating function is restored.

If you have no experience with disassembling a microwave, seek professional help.

5. Faulty Thermoprotector

The thermoprotector in your Kenmore microwave is like a watchful guardian. It monitors the heat levels to prevent overheating.

If it becomes faulty, it may trip unnecessarily or fail to reset, leading to your microwave not heating as it should.

Kenmore microwave won't heat up

How to Fix:

Start by unplugging your microwave for safety. The thermoprotector is typically located near the magnetron or the heating element.

Once you find it, inspect it for any signs of damage or wear. Use a multimeter to test for continuity. If the thermoprotector shows no continuity, it’s time for it to be replaced.

Carefully remove the faulty thermoprotector and install a new one, ensuring it’s the correct type for your microwave model.

Once the new thermoprotector is in place, plug your microwave back in and give it a test run.

If your microwave resumes heating, you’ve successfully solved the problem. However, if you’re not confident, I suggest you call a professional technician.

6. Burnt Out Magnetron

The heart of your Kenmore microwave’s heating function is the magnetron.

This essential component is responsible for generating the microwaves that heat your food.

When the magnetron burns out, the entire heating mechanism is ineffective, leading to a microwave that runs but doesn’t heat.

How to Fix:

Addressing a burnt-out magnetron begins with a careful examination. Safety is paramount, so ensure the microwave is unplugged before proceeding.

Once you’ve accessed the magnetron, employ a multimeter to check its continuity.

This test is crucial in determining the health of the magnetron.

If your multimeter reading shows infinite resistance, it indicates that the magnetron is no longer functioning and needs replacement.

However, due to the technical complexity and associated risks, replacing a magnetron is not a typical DIY task.

It involves handling high-voltage components and intricate knowledge of microwave mechanics. Therefore, it’s strongly advised to defer this repair to a technician.


Dealing with a Kenmore microwave not heating can be a hassle, but it doesn’t have to be a roadblock in your daily kitchen routine.

You can confidently restore your appliance’s functionality by understanding the common causes, from faulty diodes to a burnt-out magnetron, and applying these practical fixes.

Remember, while some issues can be tackled with some DIY spirit, others might require professional expertise.

Your Kenmore microwave is more than just a kitchen appliance; it’s a daily companion in your culinary adventures.

With the right approach and a little know-how, you can keep it running smoothly and efficiently.

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Steven Settles Author

Steven Settles is an ISCET-certified master in appliance repair. He has aced the National Appliance Service Technician Certification Exam, showcasing his exceptional diagnostic and repair skills. With an in-depth understanding of the latest repair technologies and a keen eye on evolving industry standards, Steven is a go-to expert for any appliance issue.

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