Microwave Not Heating – Causes and How to Repair

Living in a fast-paced world, we can’t deny how advantageous it is to own a microwave oven. It speeds up cooking time, it’s safe to use, and it’s easy to clean, among many other benefits. But they can and do break down. One of the most common issues with microwaves is that they can stop heating properly. In this article, I’ll address the possible causes and repairs for your microwave not heating up properly.

Three of the most common causes for microwave not heating are issues with one of the following parts:

  1. Magnetron
  2. Interlock or door switches
  3. High-voltage diode

Read on to learn more about these microwave parts and how you can check if they are causing your microwave to not heat up properly.

Also, take a look at an excellent microwave that is built to last, the Dacor Distinctive Series Counter Top Microwave:

Click here to see this microwave on Amazon.

Microwave Not Heating – 3 Common Causes and How to Repair

It’s possible to fix a broken microwave oven all by yourself if the issues involve the magnetron, interlock switches, or the high-voltage diode.

However, there are many microwave issues that would require professional help. If you run into an issue, don’t hesitate to reach out to a repair center to avoid damaging the microwave.

But first, let’s discuss the common causes of microwave not heating.

repairing microwave not heating

1. Magnetron

Let’s start with a simple situation. For instance, you’re about to reheat your food. You place your food inside the oven, close its door, and set the timer for five minutes. Everything seems to be working well.

When the alarm sets off, you open the microwave door. Then, you reach for your food, only to find out that it’s still literally as cold as ice. If you experience this, then the issue is probably the magnetron.

Invented in the 1930s by Dr. Albert W. Hull, the magnetron is a component of the high voltage circuit. It’s also the primary component of the oven, as it is the source of microwaves for heat generation. Through a waveguide, this heat travels and enters a metal cavity to cook the food. The food then absorbs the microwaves, which stir water molecules in it. This process transfers heat throughout the food.

Why Magnetons Break

There are several reasons for the magnetron to break. Here are some of them:

  1. The magnetron’s magnets tend to overheat. Overheating happens when the microwaves reflect back to the magnetron excessively. This occurrence damages the magnets and eventually reduces the magnetic field.
  2. The dome or antenna of the magnetron tends to burn out due to the microwaves reflecting back to the magnetron in an excessive manner. If the dome or antenna burns, it will stop sending microwaves.
  3. The terminal of the magnetron tends to burn out, too. This issue occurs if the insulator breaks down.
  4. One of the most common problems with the magnetron is a loose connection. A loose connection, unfortunately, results in high resistance heat. This occurrence tends to burn other installed parts near the magnetron.
  5. If the oven has internal arc-over damage, then this is a cause for a magnetron failure. This problem occurs when gas forms inside the magnetron.
  6. If you can’t figure out the specific issue of your oven, then you may have to use an ohmmeter. An ohmmeter is capable of checking the magnetron’s terminals. If there’s nothing wrong with the magnetron, the resistance indicates infinite continuity. Otherwise, there’s an issue with the magnetron.

Can You Fix a Broken Magnetron?

The magnetron can either be fixed, or if it can’t be fixed, you may need to get it replaced. It is costly to have it replaced, so you might want to check first if the issue is repairable. But make sure that the repair is done correctly. Otherwise, the same issue might arise sooner or later. Worse, it may raise more technical problems in the future.

If the magnetron badly needs replacement, make sure to seek assistance from a credible and professional technician. It can be costly, so you have to ensure that you truly get your money’s worth.

2. Interlock or Door Switches

The interlock or door switches are responsible for the power that works only when the oven door is closed. When the oven door is open, it results in a power interruption. Thus, it causes the oven to stop functioning automatically. So, these switches are the on/off mechanism of the oven.

A microwave oven typically has four interlock switches, but this is not the case all the time. Each of these switches measures an inch long. They are commonly mounted to a bracket beside the door latch. They are mostly black in color and feature terminals or metal prongs.

There are instances when the oven’s stirrer motor or fan motor continues to operate even if the interlock switch fails to work. In this case, the magnetron will stop functioning, too. Thus, the reason for microwave not heating enough or not heating properly.

Why Door Switches Break

The door or interlock switches may eventually break if you slam the oven door hard every time you use it. That’s why it’s a good idea to care for your microwave and other home appliances. They are, after all, among the most important items we have at home.

Remember that these door switches work together. Therefore, even if only one switch breaks, the entire oven won’t function well anymore. Moreover, you have to replace all the switches–even if only one of them gets damaged.

Can You Fix a Broken Door Switch?

Damaged door switches can be replaced. Here are simple steps to follow:

  1. Before you start replacing the door switches, make sure that your microwave oven is unplugged.
  2. Once unplugged, remove the cabinet.
  3. Identify which are the interlock switches. These switches have wires labeled as common terminal (COM), normally open terminal (NO), and normally closed terminal (NC). If the oven only has two terminals, then the wires feature the COM and NO labels only.
  4. Use an ohmmeter to check resistance continuity. If continuity is not present, then this confirms that the problem is with the interlock switches. Otherwise, the technical issue is probably with the other parts of the oven.

3. High Voltage Diode

A microwave not heating may also mean that there’s a problem with its high voltage diode.

Diodes are semiconductors that have several functions involving microwaves. They generate, switch, detect, and mix microwave signals. They produce a high voltage that allows the magnetron to function.

To access it, you have to remove the cabinet, which is located near the high voltage capacitor and the magnetron.

How to Identify a Broken High Voltage Diode

An issue with the high voltage diode or rectifier is one of the most common problems encountered by microwave oven owners. In fact, it is a common issue among all types of appliances. To confirm whether or not there is a problem with the diode, you have to test it using a voltmeter.

The procedure for testing is as follows:

  1. Before you begin, unplug the microwave oven to prevent electric shock.
  2. Prepare a nine-volt battery before you insert the voltmeter readers.
  3. Attach the diode or rectifier in a series circuit with the battery using gator clips.
  4. A voltage drop should occur in the diode. In this case, it should be one of roughly three volts.
  5. If the battery has the same voltage, this confirms an issue with the diode, which requires a replacement.

You may conduct diode testing all by yourself only if you are skilled to do so. It is still advisable to hire a qualified technician to do the job.

Can You Fix Broken High Voltage Diodes?

A new high voltage diode may be installed in your microwave oven to function once again. But then again, this must be done by a qualified technician. If you want to fix it all by yourself, you have to make sure that you are skilled to do so.

Here are some pointers for installing a new high voltage diode in the microwave oven:

  1. The anode side must be on the capacitor, while the cathode side must be on the ground.
  2. Keep in mind that the anode side is the positive side. Whereas, the cathode side is the negative one.
  3. Incorrectly installing the diode will result in an unsafe connection. So, make sure that it is connected in the right direction.

Most Recommended Microwave Ovens – Top Three Picks

You wouldn’t want to buy a microwave oven that malfunctions after using it several times, right? You also wouldn’t want to discover one day that you have a microwave not heating enough or at all. So, choose a durable, long-lasting microwave. Let me share with you my top three picks:

  1. The Panasonic NN-GN68KS Countertop Microwave Oven
  2. The Panasonic Microwave Oven NN-SN966S Stainless Steel Countertop
  3. The Dacor DMW2420S 24″ Distinctive Series Counter Top

1. The Panasonic NN-GN68KS Countertop Microwave Oven

The Panasonic NN-GN68KS Countertop Microwave Oven is a stylish stainless steel product that features a FlashXpress, a food warmer, a 3-in-1 broiler, and a genius sensor. It doesn’t just heat the food fast, but it heats the food evenly as well.

Click here to see this microwave on Amazon.

It also defrosts the food faster and more evenly compared to other microwave ovens. It features a large turntable that provides enough space for large casserole dishes.

2. The Dacor DMW2420S 24” Distinctive Series Counter Top

The DMW2420S Distinctive Series Counter Top is an excellent deal from Dacor. It may seem costly, but it is one sturdy product that can last for ten years before you encounter any technical issues.

Click here to see this microwave on Amazon.

The heating features may be the same as the other microwave ovens. But what makes this unit stand out is its durability. Dacor only uses high-quality materials in manufacturing products.

3. The Panasonic Microwave Oven NN-SN966S Stainless Steel Countertop

Another stylish product from Panasonic is the NN-SN966S Stainless Steel Countertop Microwave Oven. This unit features a genius sensor and built-in inverter technology. It has a larger interior capacity than other microwave ovens.

Click here to see this microwave on Amazon.

In fact, a 5-kilogram turkey can actually fit in this microwave. It’s also more convenient to use because of its numerical keypad compared to those units where you set up the timer using a dial.

Tips for Cleaning Your Microwave Oven

Just because your microwave oven is durable, it doesn’t mean that you stop taking care of it. Regularly cleaning your microwave oven is one way of making it last longer than usual. Moreover, it’s also a way of ensuring that your food is always safe to eat.

Here are two ways of cleaning your microwave oven:

  1. Steam cleaning without vinegar
  2. Steam cleaning with vinegar
fixing microwave not heating

1. Steam Cleaning Without Vinegar

In this process, you will need water, a sponge, a spray bottle, and lemon essential oil.

  • Get the sponge wet and place it inside the microwave oven.
  • Pour two ounces of water in the spray bottle.
  • Then, put a maximum of five drops of lemon essential oil to the same spray bottle.
  • Spray the lemon oil and water mixture inside the microwave oven. Be mindful of spraying it evenly and liberally.
  • Then, set the timer of your oven for roughly two minutes and turn it on.
  • When the timer sets off, just leave the oven door closed until you think the sponge is cool enough for you to hold.
  • Then, open the oven door and use the warm sponge to wipe the interior of your oven. You may use the same sponge to clean the exterior of your oven.

2. Steam Cleaning with Vinegar

In this process, you will need rubbing alcohol, a microfiber cloth, a wooden spoon or skewer, a glass measuring cup or bowl, water, and white vinegar.

  • In the measuring cup or bowl, pour a cup of white vinegar and a cup of water. Then, place the wooden spoon or skewer into the liquid.
  • Next, place it inside the microwave oven.
  • Set the timer of your oven for 5-10 minutes and turn it on. The time depends on how powerful your oven is.
  • When the timer sets off, remove the cup or bowl from the oven. Use an oven mitt for safety purposes.
  • Wipe the interior of your oven using the microfiber cloth. The steam from the vinegar and water mixture will allow you to clean it effectively without having to scrub your oven’s interior.
  • Once you’re done cleaning the interior, pour rubbing alcohol on the same microfiber cloth. Use it to clean the exterior of your oven.

Conclusion – How to Fix Microwave Heating Issues

Three of the most common causes for microwave not heating are issues with one of the following parts:

  1. Magnetron
  2. Interlock or door switches
  3. High-voltage diode

It’s possible to fix a broken microwave oven all by yourself if the issues involve the magnetron, interlock switches, or the high-voltage diode. Follow the steps and advice I mentioned earlier.

If you have any issues, you will need to contact professional help or bring your microwave to a repair center. When searching for a technician, shop around for the best price and avoid anyone who won’t give a clear cost estimate.