The microwave works, but does not heat, what is the reason and how to fix it yourself

НA microwave that does not heat food during operation is a common problem caused by operating errors, the wrong choice of dishes, poor quality equipment, wear and tear of parts, and other reasons.

To identify the problem, you need to know the features of the operation of the equipment, diagnose and fix the problem: with your own hands or with the help of a wizard.

The principle of operation of the microwave

To repair / maintain any equipment, including a microwave oven, you need to know how it works. Consider the basic elements and their purpose.

Magnetron

At the heart of a microwave oven is a magnetron, which, after switching on, produces microwave energy and distributes it throughout the interior.

The magnetron screen is located inside the microwave on the right behind the wall where the control panel is located. It is made in the form of an overlay, which is mounted on latches or screws.

The function of the screen is to protect the magnetron from food particles from the cooking zone.

The device is connected to the camera using a rectangular waveguide, which is closed with a glass or plastic cover.

Source of power

Transformers-stabilizers, which are the most complex and expensive element, act as a power source.

As additional equipment, a multiplier is used, which includes a capacitance and a diode bridge.

After applying voltage to the magnetron, the fan also turns on, which distributes warm air and thereby speeds up the cooking process.

Chassis

The microwave has a rectangular body, which is of key importance when heating.

An additional plus is the rotation of the saucer on which the food is installed. This function is provided by a special engine.

Control panel

The operation of the microwave oven is set using the control panel.

Depending on the complexity of the equipment, it can be mechanical (rotating handles) or touch (buttons).

Additionally, a number of protections are provided to ensure the safety of operation.

For example, when the door is opened, the oven will automatically stop working. There is also a timer that turns off after a certain time.

Door

In the manufacture of a microwave oven, special attention is paid to the door. The gap between it and the body should be minimal.

A high-frequency damper is installed along the perimeter, acting as a barrier to dangerous waves.

In addition, the plastic used in the manufacture is capable of absorbing radiation.

About security

Reasons why the microwave does not heat, but works

Experts identify many reasons why a microwave oven can work, but not perform the basic heating functions. Conventionally, all causes are divided into the most common, simple and complex.

To avoid confusion, we will consider them separately.

Common malfunctions

First, let’s highlight the most common explanations for the fact that the microwave oven does not perform its functions:

1. Heating food with metal elements: spoon, fork, etc.
2. Use of unsuitable utensils: metal, with a gold frame, with a lid, etc.
3. Low quality equipment and quick failure. Many manufacturers don’t bother with high quality parts to get buyers looking for new products.
4. Natural aging of microwave oven elements, etc.

Simple Causes and Tips to Eliminate Them

There are many simple faults that cause microwave ovens to malfunction.

Let’s highlight the main ones:

In this case, additional diagnostics are necessary.

Complex malfunctions, the microwave heats up, but buzzes

In more complex cases, we are talking about some kind of malfunction of the equipment. After switching on, the tray rotates, the light is on, but the microwave oven does not heat anything. There may be several reasons for this.

Блок управления

For beginners, the best way is to replace the hardware or flash it with software.

Magnetron

The most difficult situation is when the microwave does not work due to damage to the magnetron.

The failure of this part may be due to the following reasons:

1. Bad contact connection. If the contact is loosened at the connection point, heating occurs, which leads to the impossibility of normal operation. To fix the problem, it is necessary to compress the contact group with pliers.
2. deterioration of the metal. Many microwave ovens have a hole in the cap through which you can look at the metal elements and assess their condition. In case of metal integrity, the problem is in the cap, which requires replacement. If the metal is damaged, the microwave may break. The solution to the problem is to replace the magnetron, which is expensive, or buy a new microwave oven.
3. Traces of burnt or metal drops on the surface. To remove them, use sandpaper to clean the cap and in this way improve its conductivity.

Fuse

Caps are installed on the sides, to which a wire in the form of a spring is connected.

The current passes through the fuse and if this parameter is exceeded above the optimal rate, the insert burns out.

There is also a situation when the wire simply moves away, due to which the voltage does not enter the microwave oven.

Mica plate (magnetron screen)

A special plate is installed inside the heating zone, which can be visually inspected and a malfunction detected.

In addition, contamination may cause sparking or crackling. In the most difficult cases, the part may even catch fire.

Capacitor, transformer

If the microwave oven does not heat food and makes a lot of noise, in 90% of cases the cause is a blown capacitor.

If smoke appears after turning on the device, this indicates damage to the transformer.

You can talk about a malfunction with normal overheating without damaging the part.

Diode

A broken diode can heat up and damage the capacitor.

Инвертор

The purpose of the device is to determine the temperature inside the chamber and the products themselves.

In both cases, the microwave oven simply will not heat the food.

Timer

In case of damage, the timer does not work correctly and starts to randomly turn on and off the equipment.

There is no point in repairing this part, so the only correct solution is to replace it.

Diagnostics and troubleshooting

Before performing repair work, it is important to carry out diagnostics to determine the malfunction.

In a situation where the microwave does not work, turns on every other time, buzzes or does not heat, but works, do the following:

1. Check the voltage supplied to the transformer. To do this, use a regular multimeter and follow the safety precautions. If the voltage drops below 215 Volts, connect the stabilizer or wait for this parameter to normalize.
2. Check door latch for proper operation.
3. Make sure the contact connections are reliable, as well as the serviceability of the main elements.
4. Disconnect the microwave oven from the power supply and remove the upper part of the case.
5. Remove the chip from the magnetron and check it.
6. Put the terminals on the magnetron in place.
7. Check capacitor.
8. Check diodes.
9. Check the integrity of the fuses. Burnt out elements are immediately visible by blackening.
10. If the latter burns out, check the multiplier nodes.

After determining the malfunction, a decision can be made on the possibility of repairing the microwave oven.

If there is cod, do the following:

1. Determine which part is cracking.
2. Disconnect the power supply.
3. Remove the mica plate and replace it (costs about two dollars) if it is burned out.
4. Unscrew the magnetron, which is mounted on 2-4 self-tapping screws.
5. Remove the cap from the outlet. If it is tight, loosen it and remove it with your hands.
6. Look at the metal outlet under the cap for breakdown. In the presence of such traces, the magnetron must be changed.
7. If the feedthrough capacitors fail, they must be replaced.
8. If the cap is burned out, change it.
9. Replace the capacitor if it is the one that breaks through.

Repair by own hands

The essence of repair work is to check and replace faulty elements.

To access internal elements, do the following:

1. Pull the plug out of the socket.
2. Loosen the rear mounting screws.
3. Lift, pull towards you and remove the top cover.

After that, turn the device to the right side when looking at the front.

Here in the center there is a transformer, a magnetron is installed above it, a control panel on the left, a high-voltage capacitor at the bottom right, a fuse in front of it, and a diode below it.

Fuse

There may be two or three. The first is installed on the network board from above, the second is located near the capacitor, and the third (it may not be) can be installed on the control panel.

If the microwave does not work, you need to check the device:

1. Set the multimeter to dial.
2. Put one contact at the input of the fuse, and the second at the output.
3. If there is a squeak, then the device is intact. If there is no sound, you can talk about a break. If there is at least a slight resistance, the device is working properly.

Also inspect the fuse for signs of blackening. Perform a continuity test with a tester or resistance meter.

To repair, do the following:

1. Remove the cap.
2. Solder the wire.
3. Assemble the structure.
4. Check if the microwave oven is working or not.

If the problem was in the fuse, there will be no difficulties with repairing the microwave oven.

To select a suitable part, take the defective element to the store and ask the seller to pick up the same one. It is better not to buy products with thin wire, because they burn out faster.

Diodes

Touch the first probe to the contact on the side of the capacitor, and the second to the place where the part is screwed to the case. Look at the parameter on the display.

Ideally, there should be no sound. If the part rings, it is faulty.

Capacitor

Before replacing, check the capacitor with a multimeter. The number of terminals may vary from two to four depending on the model.

Set the measurement mode on the Ohm device (200 MΩ) and put the probes in the desired connectors and touch the pins of the part:

1. No value. The capacitor is broken and needs to be replaced.
2. Small parameter deviation. Penetration of the container, the need to install a new part.
3. The indicator gradually increases to a maximum. The detail is correct.

Set the dialing mode on the multimeter, and then touch the output with one contact, and the case with the other. You shouldn’t beep. If this happens, then the device is broken.

When checking the capacitor, be careful, because the part may remain charged. If the terminals are touched, current can pass through the body.

To prevent this from happening, the product must be short-circuited by closing the contacts, for example, using platypuses with tested handle insulation.

Transformer (if the microwave oven is transformer)

To check the health, check the winding for voltage. It should be 220 V.

In the case of a decrease in this parameter, the cause may be a short circuit between the turns.

There are two ways here:

1. Rewind the winding. This option is suitable for advanced users with relevant skills.
2. Purchase and installation of a new part.

The complexity is due to the need for a correct calculation of resistance and the error-free use of an ohmmeter.

Mica plate magnetron

To diagnose the problem, dismantle the screen (where it is indicated above), and turn on the microwave oven again.

If the sparks and sounds are gone and the device is working normally, then the problem is in the screen.

Magnetron

The fault is determined by inspection. Alternatively, do a little check.

To do this, remove the terminal from the connector and touch the probes to the output of the magnetron.

If there is a squeak, then the chain is whole. If there is no squeak, this indicates a break.

Next, leave one probe on the magnetron contact (on any), and touch the body with the second. You shouldn’t beep.

If this is the case, this indicates a breakdown of the feedthrough capacitors.

If you decide to purchase, take the spare part with you or copy the data indicated on the part.

magnetron cap

After the mica plate has been checked, it is important to check the condition of the magnetron cap.

The order of further actions:

1. Remove the wires passing through the magnetron (they will interfere with its dismantling).
2. Remove two power terminals, it is not necessary to remember their location (you can swap them).
3. Remove the magnetron and check the condition of the cap. The presence of soot should not be. Otherwise, the cap is changed (sold on the Internet) and after installation it is degreased with alcohol (taken in hand). In this case, the upper part of the cap should not swing the internal upper elements of the magnetron.

Install everything in reverse order.

Turntable coupler

With the help of this part, the lower surface rotates, on which the dishes with food are placed.

The presence of soot on the coupler, as well as on the surface itself, indicates that both objects were dirty and the fat accumulated on their surface overheated, causing burning.

Also, burning may appear after placing a metal cup or plate on the surface.

Repair rules

Unskilled repairs often have negative consequences in the form of health problems or aggravate the malfunction of the microwave.

To eliminate such moments, follow these rules:

1. Always relieve stress before carrying out repairs. To do this, unplug the power cord.
2. Use protective gloves made of dielectric material and capable of protecting against voltages up to 1000 V.
3. Make repairs / diagnostics with a tool that has insulated handles.
4. Do not apply power to the microwave after parts have been removed, without food, with the door open, or if a malfunction is suspected.
5. Discharge the capacitor before checking, removing or replacing. For this
6. Be careful and check the microwave oven for metal objects inside after repair. WARNING: Sparking between case and capacitor is normal.
7. Do not drill holes in the case, as this may damage the device.

Feature repair models from different manufacturers

Despite the similarity of the design and principle of operation, each manufacturer uses its own secrets in the manufacture of equipment.

With this in mind, you need to individually approach the repair and pay attention to the brand of the manufacturer.

Below we consider the features for each of the options and summarize them in a table.

How much does the repair cost

In the absence of experience, it is better to entrust microwave repair to specialists. Depending on the policy of the service center and the complexity of the problem, the cost of work may vary.

Common breakdowns:

1. Buttons do not work due to damage to the control panel – from 2600 rubles.
2. Faulty magnetron, capacitor – from 2550 rubles.
3. Replacing a fuse due to a blown during a power surge – from 2600 r;
4. Sparking in the device – from 3150 rubles.
5. Start is not pressed on the microwave oven (control unit) – from 2900 rubles.
6. Damage to the heating element – from 3200 rubles.
7. Door malfunction – from 2650 rubles.
8. Breakdown of the engine for rotating the plate – from 2550 rubles.
9. The device does not turn off (timer, switch) – from 2650 rubles.
10. The microwave oven does not turn on (electrical circuit) – from 2900 rubles.

The exact price is determined individually after the diagnosis and determination of the malfunction.

Breakdown prevention

To protect your microwave oven from damage and prolong its life, you must follow a number of simple rules:

1. Heat food only in the “correct” dishes recommended for use in a microwave oven. It is forbidden to use metal containers or utensils with a metallic, silver or gold coating. Otherwise, the risk of ignition of equipment is high.
2. Do not place anything on top of the microwave oven.
3. Do not close food containers completely during the heating process. This is important for the release of steam.
4. Do not use carriers to connect.
5. Do not play alcoholic products.
6. Do not boil/warm eggs or other foods that are restricted by the microwave manufacturer.
7. Cover food with a special cap to protect the inner surface from grease. This simple rule can significantly extend the life of the product.
8. Install the microwave oven according to the manufacturer’s recommendations.
9. Do not turn on the microwave without food inside.
10. Make slits when cooking vegetables to allow the internal juices to escape.
11. Close the doors carefully to prevent damage to the latch and other parts.
12. Constantly wash the microwave from grease and food debris, especially pay attention to the magnetron screen. Dirt accumulated on it leads to sparking and extraneous noise.

If possible, use heat-resistant dishes made of special glass.

Its features are the ability to evenly distribute heat, which allows you to cook food faster and avoid consequences.

Summing up

A microwave is a dangerous household appliance that can cause damage even when unplugged. That is why, when troubleshooting, you need to be careful and be confident in your abilities.

If the device does not work, and you do not have the proper experience, it is better to entrust the repair to professionals.

If the cause is elementary, it can be easily eliminated with your own hands. In some cases, this requires opening the case, but you need to be careful and follow the safety recommendations described in the article.

In this case, it is important to conduct a complete diagnosis, and only then proceed to work.