Microwave Not Heating Food But Runs? 4 Ways To Fix Now.


Undoubtedly, modern technology has greatly influenced our lives and offered us exceptional help. With the boons, there are certain limitations of electrical appliances. Microwaves not heating but running is surely one of them. Of course, it’s frustrating that the microwave has lost its ability to reheat things but the majority of the time, it is because of the technical issue. Therefore, to provide better clarity of the above statement, read the article till the end and acquaint yourself with the reasons, fixation and precautions that can reverse the situation of microwave, not heating. 

Reasons Why Microwave Has Stopped Heating Up

Reasons Why Microwave Has Stopped Heating Up

Microwaves are complicated appliances with various components that work together to cook your food. There can be many reasons why the microwave is not heating food but runs.

High-Voltage Diode:

High-Voltage Diode

For a microwave to function properly, A\C power needs to be converted to magnetrons to function properly. However, the high-voltage diode transfers the A\c power to D\C power. To examine the high-voltage diode use a multimeter.

When you test a high voltage diode the resistance needs to be more than the other side, if it is equal this means that the high-voltage diode will result in improper functioning. While working at high voltage, there are high chances any component will fail and a humming sound will be produced, depicting burnout. 



The magnetron is a device that converts electrical energy to microwave radiation. To test if the magnetron is working properly again use a multimeter, and ensure that the magnetron resistance bar should remain between 2 to 3 ohms. If the results are either high or low, then this is an indication that the magnetron is damaged, and the result is in front of you.

Door Switch: 

Door Switch

A door switch is used to detect whether the door is open or closed. There are many door switches which are installed in the microwave but even if one door switch cycle goes faulty, the microwave may run but may not generate heat.

Blown Thermal Fuse: 

Blown Thermal Fuse

The usage of a thermal fuse is to shut down when the microwave overheats. You might have blown up the fuse and this could act as one of the reasons why your microwave is not heating up.

Methods To Fix:

Once you have identified the cause of the problem, the next step is to fix it. Use the following methods to get your microwave to start heating the food. 

#1: Transformer Modifications:

First, unplug your microwave to avoid any electric shocks. Then discharge the high voltage capacitor. After discharging the capacitor  disconnect the six transformer wires and remove the old transformer. 

#2: Replace The Thermal Fuse:

Always unplug the microwave then open the door to remove screws. Disconnect the thermal wires and remove the old thermal fuse. Then place the wires in the correct panel and check whether the microwave has started heating.

#3: Check The Main Control Board: 

Simply begin with unplugging the microwave, then open the door to unscrew the grill. Now, remove the connector and remove the old main control board, and attach the new main control board. Then place the wires in the correct terminal. 

#4: Magnetometer Requires Urgent Replacement: 

The main reason why the magnetometer is not working is that it is damaged and needs to be replaced immediately. To begin the process,  start with unplugging the microwave and discharging all the high voltage. After that, remove all the wires that are connected to the magnetometer. Then replace the magnetometer and place the wires in the correct place.

Pro Tip: Call A Technician but Why?

The microwave is built using many complex components and when trying to fix one part with another. There are high chances that if you are not a technical expert, then you will probably not be able to replace or tighten the parts and the frequent usage will result in a complete breakdown of the machine. Therefore, if the microwave is not under warranty and you can’t fix it on your own, it is better to call a professional.

Preventive Measures To Avoid Such Problem 

Once your microwave is working, you can follow some preventive measures to avoid such problems again. 

  • Never use metal utensils in the microwave. This can be hazardous as metals can catch fire before heating your food.  
  • Always remove aluminium foil before running it in the microwave. The foil acting as a lid or covering the surface of the food will make your food toxic by releasing chemicals that can lead to death.
  • Never heat food or beverages which are flammable, as the heat will often result in numerous losses. 
  • Never keep the microwave near the heating appliance as it can lead to overheating and the presence of excess heat will cost you an arm and a leg. 
  • Never use a microwave when the door is open as it can affect the microwave energy leading to damage. 
  • Avoid using oversized food containers: due to the excessive risk of catching fire or electric shock.
  • Do not cover the vent of the microwave when it is in use: 


Are microwaves worth repairing? 

Microwaves are not worth repairing as the average cost will be between 70$ to 100$ which doesn’t include parts and it is equal to the price of the new one.

Can you reset the microwave?

Yes, you can reset the microwave by unplugging it for 2-3 minutes and then reconnecting the microwave. The machine is now good to use.

How long does a microwave magnetometer last?

How long does a microwave magnetometer last?

A microwave magnetometer lasts for about 2000 hours. This means that the microwave would be able to heat for about 2000 hours.


The breakdown of microwaves could be because of many reasons and leads to microwave heating but running. Though the majority of reasons are technical and require an immense vast knowledge of electrical appliances, it is better to call a technician to resolve the problem. If you yourself are a safety expert then, get your hands on electricity-safe gloves and you are good to go. Always first identify the problem and then look for a solution. Try to follow preventive measures to avoid such issues.

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