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Microwave ovens allow you to heat food quickly. They are very convenient and easy-to-use appliances that work well for many years. However, they can also malfunction. It can happen that the microwave oven works but does not heat the food. Let’s look at the reasons why this happens.


Causes not caused by defective parts


The mains voltage is insufficient. When the power goes out and the voltage drops, the microwave oven does not function correctly and heats only the edges of the dishes but the food remains cold.


The power grid is overloaded. This occurs when several appliances are working on the same power supply.


The microwave mode is not set correctly.

The oven door is broken and does not close properly. A gap then appears and the food simply cannot be heated. Replacing the latch on the door solves the problem.

There is a metal object inside the oven or unsuitable cookware. Placing such items in the microwave will cause sparks, in some cases even an explosion, and of course, the appliance will stop heating the food.


Causes of damage inside the microwave oven


When the microwave oven won’t heat the food and you hear strange noises, it could be an indication that some parts inside the appliance are malfunctioning. You can locate the fault yourself. To do this, first, disconnect the oven from the power supply and then carry out the diagnosis.


Fuse defective

The fuse is located inside the oven and must be removed from the back cover to see it. This part is in the form of a metal filament that is encased in a glass or ceramic tube. There are usually 2 fuses in the construction of the microwave.

If the element is defective, the tube will swell, turn black and the filament will bend. If the appearance is unchanged, the fuse’s function is checked using an ohmmeter.


If the fuse breaks it will be necessary to replace the old part with a new one.


Condenser breakage

A broken capacitor will be indicated by noise and humming when the appliance is operating. An ohmmeter should be used to determine if this part is faulty:


– If the resistance is weak – the capacitor is defective;

– if the arrows of the device remain in place – the capacitor’s contacts are missing;

– if the arrows go to the infinity point “∞” – the capacitor is OK.


Faulty high voltage diode


Measuring the resistance is a rather time-consuming process, so it is almost impossible to do it at home without expert assistance. A faulty diode can be identified by the capacitor that is connected to it. A cold capacitor indicates a faulty diode.


A broken diode is also indicated by a loud humming noise when the microwave is operating.


Magnetron damage

A magnetron is a lamp that generates high-frequency radiation and is responsible for heating the oven cavity. Failure can also occur in the capacitors or the contacts on the power supply become oxidized.


To determine the fault, the lamp housing is opened and the voltage in the transformer is measured. If the reading does not match the 220 V mark, the element is broken and will have to be replaced.


If the microwave is making a lot of noise and humming, but not heating, this could mean a broken magnetron.


Mica plate malfunction

The plate needs to cover the outlet of the waveguide through which the radiation passes into the chamber. If soot builds up in this area there will be an obstruction that prevents the waves from passing through. If the microwave oven is operated with this type of fault, sparks may arise.


If the first visual inspection reveals no fault and the operation of the main is as required, i.e. the mains and socket power are sufficient, then the microwave should be taken to a service center. Chula Vista Appliance Repair Company technicians will take the necessary measurements to pinpoint the cause of the malfunction and help correct the problem by replacing worn parts with new ones.


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