Easy Solutions: LG Microwave Problems – No Heat and Loud Sounds

LG microwaves have reliable and higher user satisfaction. Like many other brands, they have a humming operation, but not too loud to disrupt your peace. Though normal, when the noise accompanies a lack of heating, you have a cause for worry. You could be operating your appliance with errors, or there are defects that you need to test and resolve. 

LG microwave not heating and making noise could be due to a timer button that is off, half closing door, a defective latching switch, or a defective capacitor. It could also be due to a broken diode, bad magnetron, tripped thermo-protector, blown thermal fuse, or defective control board.

Whatever the issue, you must resolve it, or else you must replace the oven. So please have a look at the causes and how to fix them.

Why Is Your LG Microwave Oven Not Heating And Making Noise & How To Fix?

1. Wrong Button Selection

Errors and omissions are sometimes costly. You may have selected the wrong button when cooking—for instance, the timer button instead of the start or cook button, and so forth. Also, you may not have pressed the timer. 

This feature counts down your time and works hand-in-hand with other buttons such as cook, defrost, etc. As a new user, it is quite complex, but you have no choice. You must learn what button to press and for what. 

Selecting the timer cannot cook your food, so it will remain cold. The regular humming and countdown will continue, but the oven is not heating. A wrong button selection can leave you with the idea that your LG microwave is faulty. Begin by checking this error to avoid complex processes and unnecessary costs.

How To Fix

  • First, learn your LG microwave operations. Go through the user manual and videos to master all the buttons.
  • It is possible that you made a wrong selection. Cancel the cooking process and begin the selection afresh.

2. The Door Is Half Closed

Your LG microwave and any other oven operate with the door closed. That’s a safety design to prevent harmful radiation from reaching you. Also, a closed door prevents burns and scalds. So, the door must be latched for your oven to begin running. If there is an incomplete latch, it is rare that the turntable and heating process will happen. Also, the oven will remain silent. If there is noise, there could be other faulty components. 

How To Fix

To fix this error, you must find out why your door is not closing. 

  • Damaged Door: Your microwave door gets damaged due to mishandling, including forceful opening and slamming.

Repairing a broken microwave door is complex. You may not determine if the damage extends beyond the latch and hinges to the door switch. Call LG for repair and replacement. 

  • Broken Hinges: If your microwave door hinges break, they will be loose and hang on one side. You can even remove it effortlessly. A replacement can help, but you must consult an LG specialist to advise you further. 

3. Defective Door Switch

The purpose of the door switch is to interlock the system and interrupt electrical flow to the magnetron. That happens when you open the door. When you close, the system allows the same energy flow to the magnetron to facilitate heating. So, the functionality is a safety design, so you cannot operate the oven with an open door. 

The switch position is inside the microwave, near the door latch. When the oven door closes, the switch engages, and vice versa. This feature is to lock in high-frequency electromagnetic radiation and prevents leakage. With a defective door switch, the oven will stop heating.

How To Fix

A faulty microwave door switch will not allow you to cook. Also, it is a safety risk as electromagnetic waves can leak out of the cooking cavity. Call LG to fix the switch for you. 

If you are bold enough, order a new LG door switch and try the following procedure; 

  • Unplug your LG microwave before any repairs to safeguard yourself from electric shock.
  • To locate your door switch, use the model’s user manual, but you can check the button on the control panel or near the door latch. Different models may have specific door switch locations. If unsure, stop the exercise and call your LG customer service. 
  • If you succeeded in getting the switch location, inspect the damage. It could be as simple as a detached lever or loose wire connections. 
  • Get a multimeter and test your door switch for continuity. With no continuity, the switch terminals will not respond.  
  • With the manufacturer’s replacement instructions, the process is simple. Follow the installation instructions, reassemble, and test your switch. 
  • Plug back the unit and test if the new door switch is functioning well.  

4.  Broken High Voltage Capacitor

The high-voltage capacitor is in charge of storing electrical energy in your microwave oven. With this energy in store, the magnetron gets enough power, generating heat to cook food.

The capacitor releases the energy in short and intense shots to the magnetron. It not only powers the magnetron, but the capacitor also powers the diode. The diode is in charge of converting the high current power/low voltage into low current power/high voltage to generate microwave power. LG microwave not heating and making noise may be due to a broken high voltage capacitor.

In a nutshell, it is a regulator of power in your microwave. None of the above processes can occur if it breaks or burns out. The heating stops, and your food remains cold. There could be several issues with this crucial organ in your oven.

  • Short Circuit: A short circuit will cause the fuse to blow and the heating to stop, but the oven will not be noisy.  
  • Open Circuit: an open circuit will cause the magnetron to stop generating microwaves that heat your food. Like the short circuit, the mess will not cause your unit to make noise. 
  • Partial Short Circuit: Apart from causing the magnetron to stop generating heat waves, it will cause a loud noise. The magnetron will make a more deafening buzzing noise than normal. You will be able to notice the sound as it is not regular humming. 
  • Leakage: High voltage capacitor can leak when it is faulty. For this reason, you will hear a crackling noise. Sometimes it is a hiss. This is a safety hazard that requires close monitoring and replacement. 

How To Fix

The High Voltage Capacitor is not one that you can replace. Once it gets damaged, the solution is a replacement. Sometimes, the cost involves replacing the diode and magnetron, and being observant when cooking helps you to make informed decisions.

Listen to any cracking, hissing, and burning smell from your oven. If you suspect your capacitor is faulty, call a professional, as the unit holds lethal electrical energy.

5. The Diode Is Burnt

Your microwave oven cannot heat your food from your power source’s AC.

The energy must be high-voltage, so the unit has the diode to convert this power. Diodes are semiconductors that rectify the AC power from the reservoir, the transformer, to DC energy that powers the magnetron.

It goes without further explanation that if the microwave’s diode burns out, the magnetron has no voltage. The result is your LG microwave is not heating and making noise.

How To Fix

A cracking noise may indicate a defective or failing diode. Also, a partial short can cause a humming noise. When that happens, unplug your device and call for help. A faulty magnetron has only one solution; replace it.

6. Failed High Voltage Transformer

One of the major signs of a faulty high-voltage transformer is an electric shock when you touch the unit. Also, you begin smelling burning wires. Such symptoms indicate dangerous high voltage levels and can cause a fire.

That’s already high risk, so you should never attempt a diagnosis or repair. Have a look at all the symptoms here;

  • Power failure: A failed transformer will reveal itself without power in your oven. Though there is power in your home, the display will not light, no spinning will occur, and the unit will remain off.
  • Less or no heating: A faulty transformer will provide less or no heating to the unit. Your oven will spin and hum, but no heating will take place.  
  • Noise: A faulty transformer can make a loud humming or buzzing noise. After a while, the microwave will be quiet and stop working.
  • Burning smell: The burning smell from your microwave should send signals of a safety hazard. The transformer could be overheating, thus producing a burning smell. Unplug your LG oven and call a professional to handle the machine. 

How To Fix

A failed high-voltage transformer is not easy to fix. If the failure is not due to power loss in your home or the wall source, ask your tech to test and replace the transformer.

However, some part replacements are expensive, especially if your LG microwave is old. A common symptom will be the LG microwave not heating and making noise. Consider replacing the entire with an ultramodern microwave oven from LG or a company of your choice.

7. Blown Thermal Fuse

Electrical machines are bound to overheat. The heat can cause extreme damage to the appliance. So, what happens if your microwave oven overheats? There is an internal mechanism to protect your device from such impairments.

The thermal fuse disconnects off power to the unit if it overheats. An automatic reset allows the oven to start working when the unit cools down. The thermal fuse can blow! When it blows, the feature stops all functions, including heating.

Your oven might light up but doesn’t heat or cook your food. A blown thermal fuse might only pop once to indicate blowing, but the unit will not be noisy.  

How To Fix

You must test the microwave fuse for continuity with a multimeter to check. The process is impossible if you do not have the gadget, so you might have to call an LG technician.

With firsthand information about a blown thermal fuse, they will come with a new one. You can ask the tech to fully inspect your microwave and pick up any other underlying problems.

8. Tripped Thermo-protector

Thermal protectors are also safety mechanisms that shut down appliances when they overheat. When they trip, that means there are loose wires or short circuits. Usually, the thermo-protector will trip or fail due to a lack of ventilation. But there are more reasons;

  • Blocked Ventilation: The vents allow the microwave to breathe out hot and cool air. That cools the fan, the thermo-protector, and the entire unit.

Cool air won’t get into the microwave oven if objects or the wall blocks the bents. That overheats and trips the thermo-protector. Other than overheating, you will also experience LG microwave not heating and making noise.

  • Faulty Cooling Fan: The fan cools down the microwave. If defective, the internals will begin overheating and trip the thermo-protector. Sometimes, it isn’t a faulty cooling fan but dislodged debris caught between the blades or at the base. 

The fan stops or clips against the wiring, causing a rattling noise. You must open the oven and access the feature. A physical examination can help you analyze the problem and discover other issues causing your appliance not to heat and make noise. 

But before you attempt anything, disconnect the unit from the power and discharge the capacitor. Access the cooling fan by first unscrewing the components that obstruct the feature. After inspecting and fixing, ensure that it spins freely and that no debris and obstructions are near the base and blades.  

  • Defective Thermostat: The thermostat controls the temperature in the microwave. It turns on the heating and cooling system to maintain a suitable temperature in the unit. A faulty thermostat will not allow the right temperature in the oven. When it is supposed to cool the system, it will heat it and vice versa. 

How To Fix

Replace a defective thermostat and establish the case for the faulty fan. You will find the features in the internals of your microwave.

If you do not have the knowledge and skills to perform the tests and replacements, call an LG technician. They are waiting for you to contact them for assistance. For blocked vents, remove all the objects blocking your appliance.

Also, position your LG microwave a few inches from the way. That leaves a free breathing space.

9. Defective Main Control Board

The main control board is the centerpiece of your LG microwave. It controls all the functions, including the heating, and cooking programs, turning on and off. Old age, overheating, impact, short circuits, and many other causes can damage the unit. 

How To Fix

Determining the problem is difficult, especially if your unit is new. It could be factory defects. So, we recommend an LG appliance repair technician inspect your microwave’s control board and replace it or advise on the next action.  

10. Parts Deterioration

Many people overlook the fact that microwaves depreciate over time. The parts can dwindle in operation, and some break down. That includes the heating components. One of the symptoms that the unit will show is slow heating and noise operations.

Eventually, the unit may stop heating and become unresponsive to repairs and part replacement. So, your LG microwave not heating and making noise may be due to parts deterioration. You can inspect the type of noise and where it comes from with anticipation of repairing the failing components.

With a few repairs, you can save a few dollars, but unit replacement remains the better option. It will save you from great losses and inconveniences. LG has high-tech microwave ovens, including the Alexa series. You can contact them for the newest gadgets. 

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