Why Is My Microwave Not Heating Food Up?

Why Is My Microwave Not Heating Food?

Perhaps, you have been faced with the problem that you have turned the microwave oven on but after several minutes, you notice that the food has not heated. But why microwave does not heat the food? This passage could help you to figure out the problem and find the appropriate solution,

In this post, we will discuss questions including why my microwave does not heat up? My microwave works but why it does not heat my food? How to repair a microwave which does not heating food?

Very important point: repair and replacement of components inside microwave require high expertise. Microwaves oven need a voltage of 220 v for operating. Since voltages higher than 30 volts is dangerous for human and even cause death, thus microwaves are considered as one of the most dangerous home electrical devices. Hence, if you don’t have enough experience and knowledge in the electronics field, never try to repair a microwave and ask a technician to repair it for you.

Read the guide to solving “Microwave Not Heating” problem in this article from RepairLand.

How does the microwave heat the food?

Microwaves utilize a kind of electromagnetic radiation to heat food. Microwave oven energy passes through glass, paper, plastic, and similar products and is absorbed by food. Microwave heat food by emitting radiation to water molecules that existed in foods. The heated food by inducing friction between molecules of food. Microwaves cause vibration and friction in a water molecule, which in turn generate heat. Microwave radiation is generated by a tube which is called a magnetron.

Reasons for which microwave does not heat food:

  • Diode failure
  • Magnetron failure
  • Door switch failure
  • Voltage transformers
  • Capacitor

If your device does not heat food, one should check above mentioned component to detect defective components and replace them in case of need,

Diode failure

In a microwave oven, the diode is combined with a capacitor to neutralize the volage, which is necessary for a magnetron power supply. If the diode fails, the microwave will not be supplied anymore and thus can not heat foods. Diode converts AC power output to DC power and increases voltage approximately twice. Magnetron uses this voltage to heat your food. If the diode fails, burns, or does not work for any reason, the magnetron will not receive adequate and required voltage to heat foods and finally, the microwave does not heat foods. The good news is then in case of diode failure, one could observe it easily, in this situation, the only solution is to change the microwave diode which essentially should be done by an expert and skilled technician.

Magnetron failure

Magnetron uses high DC voltage and current to heat food. Hence magnetron is vulnerable to failures. The magnetron is an important component in microwave heating performance. If your magnetron fails, it should be replaced. Since microwave works with high voltage and high voltage capacitor is an ability to preserve charge for a long duration, there may be a voltage in the microwave, even when it is turned off. Thus, magnetron replacements require high expertise and skill and necessarily should be performed by a trained technician, otherwise, it could result in electrocution and electrical shock. Additionally, magnetron repair costs a very lot and is considered an expensive repair.

Door switch failure

Microwaves have 3 or 4 door switches. These switches were designed to ensure complete closure of the door and are activated when the door is closed. This is a safety mechanism for the microwave to not generate and harmful radiation when the door is opened. When you close the microwave door, ensure complete closure and safety of door switch, since in case which door is not closed correctly, microwave will not be turned on at all, and thus it would not heat the food. Also, if one of the switches does not work, the microwave will not heat up. Utilize a multimeter to check whether the switches are broken, and in case it needs, you should replace the door switch. Notice that door switch replacement should be done by a technician.

Voltage transformers

It is possible that (high voltage) voltage transformers of your device are failed and are not working. In microwave, the transformer is responsible for supply required electricity for magnetron operation. This transformer utilizes winding two to amplify electricity from 220 volts to 2200 volt. This component is very dangerous and should be assessed by a microwave oven repair expert.


In case of capacitor failure, the microwave will not heat food. Capacitor stores electricity to supply power of volage transformers in case of need. The defection of the insulator inside the capacitor, short circuit of two-pole, and not charging are the main reasons for the failure of this component.

The points mentioned above are among the most common reasons for microwaves not heating.

important point before troubleshooting microwave that not heat

The important point you should know before assessing and troubleshooting of microwave

  • Unplug microwave electricity before any assessment and repair.
  • In case of observation of any dirt or seal damage of door which does not allow correct closure of the door, do not turn the microwave on and do not use it at all, and quickly repair or replace the door.
  • In case of failure and breakage of the glass door, the microwave may turn on, but it could pose some serious damage to you due to leakage of very dangerous radiations.
  • In case of need to replace components, make sure to use components recommended by producers and designers of product and essentially use original components.
  • In case of failure of one or multiple components, it is better to buy a new microwave oven. Repair costs of the microwave are too high and repairment is not efficient.

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