Is Your Kenmore Microwave Not Heating Up? Here’s Are 4 Ways to Fix It Fast

If you own a Kenmore microwave, you know how helpful it can be for quickly reheating leftovers or defrosting frozen food. But what if your Kenmore microwave isn’t heating up? A microwave that does not heat up can be extremely inconvenient, and it is critical to identify the root cause of the problem to resolve it. 

By knowing the cause of the problem, you can easily repair your Kenmore microwave and get it back up and running in no time. So, if you’re having trouble with your Kenmore microwave not heating up, keep reading for some potential solutions.

4 Most Common Reasons Why is Your Kenmore Microwave Not Heating Up

1. High Voltage Diode Has Burned Out

The high voltage diode in a Kenmore microwave is an important component that helps to regulate the high voltage in the microwave’s magnetron, which then generates microwaves for cooking. The high-voltage diode assists in the conversion of an alternating current supply into a direct current supply, which is required for a magnetron to function.

However, if the high-voltage diode has burned out, the AC supply will not be converted into a DC supply, resulting in a non-functional magnetron. And this will lead to the Kenmore microwave not heating up problem.

Also Read: 5 Best Over The Range Microwave Convection Oven Combo


Before proceeding with the solution, you must unplug the microwave oven. Furthermore, make sure that the microwave is not hot. 

  1. Remove the outer casing by unthreading the mounting screws and unclipping the case from the main body.
  2. Make sure to discharge the capacitor, as it may carry a deadly charge even after the microwave is unplugged. We would recommend you wear rubber gloves while doing this. Alternatively, it would be ideal to ask for help from a professional. 
  3. You can use a needle nose plier or a screwdriver to discharge the capacitor. The capacitor will look like a cylindrical component with two wires attached near the magnetron.
  4. Discharge the capacitor by shorting the terminals of the capacitor with a screwdriver, or you can also use a capacitor discharge tool.
  5. To short the terminals with a screwdriver, touch the tip of the screwdriver to both terminals at the same time until the capacitor is discharged.
  6. Once the capacitor is discharged, it is safe to proceed with working on the microwave.

Note: It should be noted that discharging a capacitor can be a dangerous task that requires a thorough understanding of electrical systems and appliances. Hiring a qualified appliance repair technician is best if you are not comfortable or experienced working on appliances.

Fix the High-Voltage Diode

Now that you have discharged the capacitor, you must inspect the high-voltage diode. It is attached to the capacitor, which you have already discharged.

  1. Once the capacitor is discharged, you can use a plier to pull off the high-voltage diode from the capacitor. 
  2. Then, unmount the other side of the high-voltage diode from the support bracket.
  3. If the high-voltage diode has been burned out or damaged, you need to replace it. You can check it using a multimeter by setting the measurement to resistance (Ω) and touching both terminal probes of the diode.
  4. If the diode needs to be replaced, the multimeter will reflect the same resistance in both directions.

To replace the high-voltage diode, check out this video:

2. Faulty Door Switch

A door switch in a Kenmore microwave is a safety feature that prevents the microwave from operating when the door is open. If the door switch is faulty, the microwave may not start or may continue to run even when the door is open. Here are the steps you can follow to replace a faulty door switch in a Kenmore microwave:

  1. Unplug the microwave.
  2. Take out the metal strip on the front top of the microwave door by unthreading the mounting screws.
  3. Then, disconnect the control panel by unmounting the screws and disconnecting the wire harness.
  4. Use a multimeter to test the resistance. If the door is open, it will show infinite resistance. However, if the door is closed, it should be zero.
  5. If the infinite resistance is showing on the multimeter, you need to replace the door switch. 
  6. The door switch is a small, rectangular component with two or more wires attached to it.
  7. Remove the wire and gently pull the switch out of the socket.
  8. Install a new door switch in the socket and connect the wires.
  9. Resemble the microwave and test to see if it’s working or not.

Also Read: 5 Best Microwaves Under $100 [Top Rated] In 2022

3. Broken Magnetron

A magnetron is a component that generates microwaves which then allows you to heat the food. If it’s broken, the Kenmore microwave will not heat up. However, if it’s not broken, you must check the thermal fuse.

Here is how to fix a broken magnetron in a Kenmore microwave:

  1. First of all, you have to remove the microwave casing by following the steps given above and then discharge the capacitor. 
  2. Locate the magnetron in the Kenmore microwave, which is usually present in the center of the microwave. 
  3. Test the magnetron’s continuity with a multimeter after disconnecting the power cord from the socket. If the resistance is infinite, you need to replace the magnetron.

Kenmore 12664F Microwave Magnetron

If you are going to replace the Kenmore microwave magnetron, then you will need the replacement component, which is not easy to find in the local market. So, here we are linking a Kenmore microwave magnetron that you can use as a replacement part while fixing your own Kenmore microwave.

Below we have shared a video on how to replace a magnetron in a Kenmore dryer. Have a look:


After reading this blog post on Kenmore microwave not heating up, you should have a better understanding of the possible causes of the problem, as well as how to troubleshoot and repair them. 

Kenmore microwaves can be repaired by following a few simple steps, whether the problem is a faulty door switch, a blown fuse, or something else.

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