Comprehensive Guide to Microwave Oven Not Heating Up Food But Runs

A microwave in your kitchen is the most common home appliance, used several times a day to heat food. This easy-to-use appliance takes less space and fulfills your several needs. Microwave is found in almost every kitchen, used to cook and heat the food. 

However, due to the constant use, it is prone to show some faults after some time. A common fault or problem that occurs with microwaves is the “microwave not heating” issue. This issue can occur due to many reasons. In this article, you will learn how to fix this issue effectively and smartly. My DIY Decor always aims to give easy and perfect solutions to your problems that ensure a good lifespan to your product and fix the issue too. Here are common reasons for your “microwave not heating food but runs” problem and effective solutions.

How Does a Microwave Work?

Before digging into the causes and reasons of microwaves not heating properly, we need to understand the working of a microwave. There exists a magnetron in every microwave that is responsible for producing high-frequency radio waves. The waveguide directs these waves into the metal box or the food chamber. 

When these waves come in contact with water, they are absorbed by the water. The waves have the right frequency to fiercely vibrate the water molecules that cause heat; by following this process, the food is heated.

Microwave Not Heating Food – Reasons and Solutions

Common issues and their solutions to fix a microwave

A burned-out diode

A burned-out diode

A burned-out diode is the most common reason for the microwave’s improper or no heating; the high voltage diode in the microwave powers the magnetron. To check out your diode, see the cabinet where the diode is located. Before going for the inspection, unplug the microwave to avoid any injury. 

Get a multimeter to check your diode. If the resistance in your diode is low in one direction and higher in the other, then your diode is working fine; otherwise, you need to replace it.


Note down your microwave model and purchase a new high voltage diode to replace it with the old one. 

The issue with the magnetron

The issue with the magnetron

Another possible issue when your microwave is not heating can be the damage to the magnetron. It won’t be wrong to say that the magnetron is the microwave’s core part, responsible for cooking or heating the food. If the magnetron is damaged, then your microwave won’t heat, which could damage the other microwave components. 


To know the real problem, you need to access the magnetron by removing the cabinet. Unplug the microwave and discharge the high voltage capacitor to avoid electric shock. Disconnect both wires of the magnetron and use a multimeter to check the continuity in it. Only 2-3 ohms of resistance should be there in the magnetron. If there is no continuity in the magnetron, you need to replace it. 

If there are no continuity defects in the magnetron, then you need to call a professional as it may require live voltage tests.

The door switch is faulty

The door switch is faulty

If you are still unable to get the fault in your microwave, then it’s time to look at the microwave door switch that might be creating problems for you. The interlock or the door switch is located inside the cabinet. 


Unplug the microwave and remove the cabinet to access the door switch. Take the multimeter to check the continuity. For this, you need to depress the actuator button and then check the continuity. If there is no continuity, then there is a need to replace the interlock. Also, when checking it, you need to make sure that the door switch is working properly.

Frequently Asked Questions (FAQs)

  1. Can I fix my microwave at home?

Yes, you can fix your microwave by yourself, but hiring a professional to inspect your electronic device is a better option. As the microwave can create a risk to your life, it is better to look for a technician. Moreover, depending on the situation, it may be good to buy a new microwave instead of spending a huge amount on its repair.

  1. What are the main causes of microwaves not heating?

If your microwave not heating food but runs, it might have a damaged diode, faulty door switch, or some issue with the magnetron. 

  1. Is the repair of the microwave expensive?

The repair is not very expensive in case of an issue with the door switch or the diode. However, if the magnetron is damaged, then it can be expensive.

  1. What are the signs that the microwave is in bad condition?

Your microwave is demanding a repair if you notice:

  • The food is not properly cooking or heating
  • The buttons of the microwave are not working
  • The microwave makes some horrible sounds while cooking
  • Some smoke, sparks, or burning smells.