The microwave works, but does not heat: reasons and solutions

It is difficult to imagine modern life without a microwave oven. If the equipment suddenly breaks down, then a slight panic begins, morning delays due to a long breakfast, and even the usual diet changes.

The most common problem is that the microwave works, but does not heat. There can be many reasons - from trivial improper operation to serious breakdowns. Let's figure out what to do in each specific case and how to fix the equipment.

Why doesn't the microwave heat up?

The most common reasons for equipment failure to perform its direct functions are quite banal and are based on improper operation of the microwave. Several points can be highlighted here:

• heating dishes together with metal objects;
• heating dishes in unsuitable containers - for example, with a gold rim or a tight lid;
• cheap and low-quality equipment - manufacturers specifically make it so that it is easier and cheaper to buy a new unit than to repair an old one;
• wear and tear of parts over time.

The principle of operation and design of a microwave oven

To understand why the microwave stopped heating and how to fix it, you need to understand the design of the equipment.

Microwaves, namely high-frequency radiation that heats food, are created by a magnetron. It is connected to the camera by a rectangular waveguide, which, in turn, can be covered with a mica plate or a plastic cover.

The power supply is provided by a transformer, which is assisted by a multiplier consisting of a diode bridge and a capacitor. The fuse protects equipment from overloads and short circuits. The fan cools the magnetron and drives warm air into the chamber, which speeds up the heating of the dish.

You can set the mode and time for heating food on the control panel. It can be either mechanical or sensory.

Checking feed-through capacitors

They are placed on a high-frequency lamp. First, they are discharged by closing the output of each container to the housing with a screwdriver with a plastic handle. Then, using an ohmmeter, one probe of which touches the housing and the other the capacitor terminal, the serviceability of the elements is checked. If the reading is 0.1 ohm, the part is working. When zero it will have to be replaced. By connecting the microwave to the network and placing a glass of water in the chamber, at the same time they check the primary winding of the transformer. The voltage at its terminals in heating mode should be 220 V.

Checking thermostats.

The simplest causes of problems and tips for eliminating them

Microwave oven spins but doesn't heat food? In addition to the lack of heating, pay attention to additional signs - for example, the microwave is humming or making a lot of noise.

First of all, you should look at the instructions, since they contain tips that can help you understand the reasons for the malfunction of the equipment. But the main problems are similar, so we will analyze them. Let's start with the simplest breakdowns that can be fixed at home.

Insufficient voltage

The required voltage in the network for proper operation of the microwave is 220 V. If this figure is lower even by 5-10 V, then the equipment will heat poorly, weakly, or every once in a while - depending on the voltage value. To prevent such surges, it is necessary to install a voltage stabilizer.

Another option in which a lack of voltage may occur is to connect large household appliances such as a refrigerator or washing machine to the same outlet, or even use a double/tee. Such actions are unacceptable, since the microwave oven must have its own free outlet.

Technical difficulites

It happens that the problem is not in the microwave oven itself, but, for example, in the wire or socket. To make sure that this is exactly the problem, you just need to connect the equipment to another outlet and carefully inspect the cord. If problems are found, either the outlet or the cord will need to be replaced.

Door

The microwave is designed in such a way that it will never turn on when the door is open. This is facilitated by special latches on the doors. If they are broken or simply do not fit tightly, then the microwave may not heat the food as well or may not heat the food at all. In this case, there are only two options - change only the latches, or the entire door.

Wrong mode

The reason that the heating in the microwave does not work may be due to ordinary human carelessness. This happens if the previous action of the microwave was defrosting, and then they forgot to turn off or change the function. In this mode, food will never warm up. All that is required in this case is to set the heating mode and, if necessary, increase the power.

If all of the above points have been checked, but the microwave still does not heat food or does it poorly and for a long time, then, most likely, a really serious breakdown has occurred, which is not always possible to fix without a professional.

How to fix simple problems yourself

How can this be? The microwave seems to be broken, but continues to work: the plate is spinning, the lights are on, and the food is cold.

The device stops heating for several reasons. Before disassembling the housing and looking inside the microwave, you should study the operating instructions, which indicate the most common breakdowns and how to fix them. First, let's deal with the simplest problems:

1. One of the common reasons why a microwave oven stops heating is insufficient voltage. For normal operation, the device requires a voltage of 220 volts, a decrease of which by just 10-20 volts will be insufficient to heat food. This can be eliminated by installing an uninterruptible power supply.
2. Network overload. To prepare food, especially on the eve of the holidays, several electrical appliances are often used. Some sockets are not able to withstand such a load, so the device does not work fully or turns off altogether. In this case, do not use tees and carriers, but connect each device to a separate outlet or use it in turn.
3. Door latch malfunction. In order for the door to fit tightly, you need to adjust the latch.

If such causes have not been found or have already been eliminated, and the stove still does not heat, then the problem lies even deeper.

Serious faults

In this case we are talking about the components of technology. They fail, so the glass tray spins, the light is on, but the microwave does not heat. Let's figure out how to understand what exactly is broken and how it can be fixed.

Fuse

A fuse malfunction is not a big deal, since it is designed to absorb the entire blow, thus protecting more expensive parts.

It is usually hidden in a special protective casing, since it is part of a high-voltage circuit. It is a small glass flask with metal caps at the end.

A wire twisted with a spring is attached to these caps so that the blow falls precisely on the fuse. If it breaks, the whole problem lies in the fact that the wire comes off from one end or the other.

Upon inspection, there should be no visible signs of fuse failure, for example, blackening or a burnt smell. The part can be tested with an ohmmeter or tester. If there is at least a little resistance, everything is fine. If not at all, then the fuse must be replaced or repaired. The last option is suitable only for those who have soldering skills.

To repair, you need to remove the cap and solder the wiring in place. After this, it is worth collecting everything in its original form and checking the functionality of the equipment. The procedure is simple, so most often the microwave starts.

Magnetron

The magnetron is one of the most important components of a microwave oven. There may be several problems associated with it:

1. Weak contacts - they heat up, so the equipment disrupts its operation. In this case, you just need to squeeze them a little with pliers.
2. Drops of frozen metal or traces of burning may form on the cap of the magnetron antenna. It is worth getting rid of them using sandpaper, which is used to polish the entire cap until it shines - the higher its conductivity, the better the performance of the equipment.
3. If there is a hole in the cap, then it must be removed and the condition of the metal located under it checked. If the metal is intact, then the problem is only in the cap - it needs to be replaced. If the metal is damaged, then the microwave fails. There are two options to get out of the situation - replace the magnetron (expensive) or buy a new microwave oven (also expensive).

Mica plate

This plate is located inside the heating compartment, so it is easy to check even just visually.

Often, with insufficient care of the equipment, carbon deposits form on it and fat accumulates, which interfere with the normal operation of the microwave. They can cause a characteristic crackling sound and even sparks. If the situation is completely neglected, a fire may occur.

This problem can be easily dealt with - sandpaper will help. You just need to unscrew the plate with a screwdriver and then clean it to perfect condition. After that, screw it back and check the functionality of the microwave oven.

Sometimes you can notice holes in the plate. They are often accompanied by an unpleasant odor and sparks. This situation can only be corrected by purchasing and installing a new part.

Capacitor

If the microwave not only does not heat up, but also makes a lot of noise, most likely the capacitor is broken - it has burned out. Its serviceability is checked by measuring resistance using a tester:

• if the arrow does not move, this is a break, the capacitor is definitely not working;
• if there are slight deviations of the needle, the capacitor is broken, it should also be replaced;
• if the arrow approaches the “infinity” icon, the capacitor is working.

Diode

The second reason why a microwave may not heat, but still hum, is a diode failure. Usually it is accompanied by a large release of heat from the condenser - it will become hot. But it is difficult to fully test this theory, so the diode is replaced even if it is simply assumed to be broken.

Transformer

If a large amount of smoke is generated, there is no need to guess what has broken down - we are talking about a malfunction of the transformer. If it breaks, there may be no smoke, but the food will still not heat up.

In this case, check the winding - its voltage during operation of the furnace should be 220 V. If the value decreases, then we can talk about an interturn short circuit.

It is possible to make a new winding for a transformer, but this is a complex process that requires special skills and effort. It’s easier to buy and install a new part, otherwise the stove will remain faulty.

Inverter

The inverter is a smart system that itself determines the temperature of the food and the required degree of heating. This is done with the help of sensors, which can break down and give incorrect data - the equipment simply will not heat up the food. That is, we can say that it is the inverter that makes the microwave operate in a specific mode.

If the inverter breaks down, it is simply replaced with a new one.

Control block

The problem with a control unit failure is that only a professional can determine it. An ordinary person should definitely not go there himself, since there is a risk of making things worse and damaging expensive parts. The control board can be replaced or simply reflashed.

Timer

A broken timer lives its own independent life, so it decides when to stop heating food and whether it is worth doing it at all. The part needs to be replaced, for this it is best to contact a specialist.

Visual assessment of the scale of the problem

This is the first thing you have to do before any equipment repair. Based on the characteristics of the malfunction, the potential culprit is quickly identified.

1. The microwave does not turn on. Most likely the fuse needs to be checked and replaced.
2. The oven turns on and off on its own, or refuses to turn off. The vent is clogged or the relay needs repair.
3. The device works, but heats too little. Sources of trouble are magnetron or voltage surges.
4. The device does not heat up, but there is light and the plate is spinning. The culprit is a dropped voltage or a circuit that requires calling.
5. The plate rotates, but it does it strangely - jerkily. The engine is faulty or the problem is caused by grooves covered with dirt.
6. The timer is ok, but the microwave does not heat. The problem may be that the door is locked.
7. There is a burning smell and the device sparks. The mica gasket urgently needs cleaning.
8. The oven is working, but the display is acting up: it does not reflect all the indicators. The problem is in the screen.
9. Neither the microwave nor the display functions. The fault lies with the damaged processor.

If the buttons cannot be pressed, they will have to be replaced or soldered.

Fault Detection

If you still have questions about how exactly to find a breakdown, you can follow the following instructions:

1. Measure the voltage of the outlet to which the microwave is connected - even minor deviations can greatly affect the operation of the equipment.
2. Check the operation of the door latches.
3. For a de-energized microwave, remove the top cover to gain access to the internal parts. If repairs are required, remove the back cover.
4. Check fuses visually. Burnt specimens are immediately visible - they are swollen and black. If there are no such traces, then you need to check the resistance with a tester.
5. Check the voltage in the capacitor and diodes with an ohmmeter.
6. After the microwave has completely cooled down, visually check the magnetron and its contacts. If there are no external problems, then it is worth assessing the resistance of the threads.

Checking fuses

To get to them, you need to remove the back cover by unscrewing the mounting bolts. First, check the mains fuse. If it burns out, the light in the camera will not light. If it is not smoked and upon visual inspection the wire inside is intact, it would not hurt to check with an ohmmeter to be completely sure.

It would also be a good idea to check the integrity of the power cord and plug. Then the high-voltage fuse located under the casing is checked, again with an ohmmeter. The presence of a small resistance indicates that it is intact. Faulty fuses are replaced with new ones, but not with “bugs” that can cause a fire.

DIY repair

There are not many problems with a microwave oven that you can solve yourself. If you are unsure of your abilities, it is better not to start repairs at all. Before you pick up something to do, you need to check it for charge.

The essence of self-repair is only to replace broken parts with new ones. You won’t be able to repair the parts yourself without experience. The operating principle is as follows:

• The fuse is a simple and cheap consumable that performs very important functions, so it is advisable to replace it at the first sign of a problem. To select a suitable part, it is recommended to take the spoiled part with you to the store. It is best not to use specimens with thin wire - they are not as reliable;
• capacitors - easy to check with a capacitance measuring device, and also easy to replace. Caution: The capacitor may retain an electrical charge for a long time, which may result in electric shock;
• diodes - it is difficult to thoroughly check their performance, so they are replaced if there are no other objective reasons for the food not heating. It is easier to replace the diode than to examine it at home;
• magnetron - easy to replace, but the purchase itself can be expensive. It makes sense to think about buying new equipment. If you decide to buy a part, then you should take the spoiled copy to the store or at least copy its serial number;
• transformer - replacing it with your own hands is dangerous. Not recommended for beginners - because... This is a complex procedure that requires basic knowledge of electronics (you need to be able to calculate the nominal resistance of the transformer windings and use an ohmmeter).

A win-win option is to call a specialist. He will always accurately, quickly and without problems determine what exactly the breakdown is, and will also immediately repair the microwave, if you do not have to order rare parts. The easiest way to “accept” the work of a master is to simply warm up a glass of water.

Repair rules

In order not to harm the equipment and yourself during repairs, you must follow a few simple rules:

1. Always unplug the cord from the outlet before starting repairs.
2. Use protective dielectric gloves.
3. Only use tools with insulated handles.
4. Do not operate a disassembled, empty, open or broken microwave oven.
5. Discharge the capacitor before repairing.
6. Don't forget any metal objects inside.
7. Do not make holes in the housing.

We are looking for a technical reason

If the microwave oven is inspected and you do not find anything preventing rotation, you will have to look for technical problems. Most likely, the microwave oven will need repairs, the complexity of which is again determined by the source of the breakdown.

It is logical to assume that the stoppage of movement is due to a malfunction of the torque mechanism. But the problem can be caused by even such a trifle as a burnt-out interior light bulb - this is what owners of older generation microwaves face. Look for problems that led to the stop in the following components and parts:

Gear. A broken gearbox is one of the most common causes of a pallet stall. Replace it. If this does not help, you will need serious and expensive repairs - replacing the engine. Considering the cost of such repairs, it is cheaper to recycle the old device and buy a new one. This way you won’t have to spend money on repairs; you will purchase a new, more reliable and functional model from a reliable manufacturer.

• Clutch. This connecting mechanism, slipping on the shaft, can interfere with rotation. Try to strengthen it by eliminating slippage. Did not help? Then you need to change the clutch.
• Motor winding. If it is torn, professional intervention will be needed. The winding cannot be restored; it needs to be replaced. You can radically solve the problem - change the motor. You can find out about damage to the winding without disassembling the equipment - the smell of burnt varnish appears.
• Power circuit. To check the integrity of the power circuit, test the wiring with a tester. Did you find an open circuit? You just need to eliminate it.

Features of repair of some brands

The causes of breakdowns for different brands are identical, but the repair of a certain brand may differ slightly from its analogues. Let's look at the features of the most popular brands of microwave machines.

Also popular brands of equipment include:

• Sharp is a popular brand with a wide range of sizes, but the actual size of the camera may be smaller than stated;
• Supra is a budget equipment with normal quality, sometimes breakdowns occur, but most customers are satisfied;
• Elenberg is also a budget brand, but has a short warranty - only for a year;
• Bork - models are distinguished by high functionality and stylish appearance, but we must take into account that the brand is Russian, and the spare parts are Chinese;
• Scarlett is a British brand that wanted to produce equipment in Russia, but still chose China;
• Daewoo is one of the leaders in electronics, simple controls and stylish models, low cost and good quality. There are retro models;
• Erisson - simple, concise and budget models. Ideal for a cottage or rented apartment;
• Vitek is a very popular brand, there are many models with different numbers of functions.

How much does the repair cost?

Even if the repair is done with your own hands, it will still require small expenses - at least for new spare parts for the microwave oven. But it’s difficult to call such expenses significant:

• about 50 rubles for a fuse;
• 100–150 rubles - for a capacitor;
• 15–200 rubles - per diode.

The most expensive part is the magnetron - it will cost 1,500–2,000 rubles. A more specific cost depends on the brand and model of equipment.

Not all problems can be solved by yourself; you may have to contact a specialist. The prices are approximately as follows:

• 200–250 rubles - cable replacement;
• 300–350 rubles - replacement of sensors;
• 400–500 rubles - door repair;
• 500–600 rubles — repair of the waveguide;
• 650–700 — replacement of the heating element.

Of course, these are average prices, which may vary by city.

Fault prevention

To avoid malfunctions in the operation of the microwave oven, you need to read the instructions for using the equipment, and also adhere to simple rules:

• choose the right dishes - exclude metal containers and even metal coating, gold and silver inclusions. The equipment may begin to spark inside and even catch fire;
• Do not close containers tightly - another requirement for dishes. The steam should escape easily;
• do not heat alcohol;
• do not use extension cords;
• do not use the microwave as a stand, despite the flat top cover;
• place the microwave correctly, following the manufacturer's instructions;
• When baking vegetables with skins, make cuts with a knife;
• do not turn on an empty microwave - this is harmful to equipment;
• do not try to reheat or boil eggs and other food unsuitable for microwaves;
• do not slam the door to avoid damaging mechanical parts;
• use a special plastic cap - this will help avoid contamination, simplify maintenance and extend the service life of the microwave.

The best microwave cookware is made of transparent heat-resistant glass. It is this material that promotes uniform heating. If you use only such dishes, then you can forget about problems when the stove heats the food and not the plate, or does not heat the middle.

Practice shows that food is best heated in transparent oval-shaped containers. Of course, other items made of glass, porcelain, ceramics and even special plastics - polypropylene, polyamide - are also suitable.

Preventing damage

We looked at how to determine the cause of a malfunction, as well as how to repair a Sharp microwave oven with your own hands. Now is the time to talk about prevention, which helps prevent failure of the basic components of the stove. You can avoid serious damage by following a few simple tips:

• Under no circumstances should food be heated in metal containers;
• do not turn on the oven without placing a dish or product in the heat chamber;
• You can’t heat eggs;
• heat food in plastic containers with lids.

These are the basic rules for operating microwave ovens. More useful information can be found in the user manual and technical documentation.