8 Reasons why LG Microwave Is Not Heating and how to fix

LG microwaves are well known for combining technology and user-friendly design to offer efficient cooking solutions. However, sporadic issues like failure to heat may result from various things, such as damaged waveguide coverings, uneven door sealing, or broken parts. There are straightforward fixes for the problem: LG microwave is not heating. Examine the door, fuse, and diode to identify any issues. Call an expert, check the fuse, and firmly shut the door if required. The microwave might not heat for other reasons as well. Users can troubleshoot by ensuring the closure is correct, looking for damage, or checking the power levels. Professional servicing might be necessary if issues continue. LG’s commitment to quality in their microwave lineup, which they created to enhance kitchen experiences with innovation and dependability, ensures such occurrences.

LG Microwave is not working but has power?

There could be several reasons why the microwave runs but does not heat, including a broken magnetron, a bad high-voltage diode or capacitor, problems with the door switch system, the waveguide cover, or the thermal cutoff fuse. To resolve the issue, look for any apparent damage, confirm that the door is shutting correctly, and examine the user handbook for troubleshooting instructions. Ask for expert help from LG’s service center to identify and fix the root of the issue if it persists.

More About Microwave Posts:

Can Is It Safe To Microwave Paper Towels

Whirlpool Microwave Stopped Working Suddenly

Eight reasons why LG microwave is not heating and How to fix them

There are eight typical reasons why an LG microwave won’t heat, and locating and replacing broken parts is crucial. Any mistake with a microwave can be fatal because it uses high electrical voltages. Take the following actions to determine the issue:

1. A burned-out diode in a microwave oven

In a microwave oven, a burned-out diode can prevent the magnetron from receiving the proper voltage, leading the microwave to malfunction. Most microwaves contain diodes near the high-voltage capacitor. The product number and type printed on the appliance can help you identify the various diodes used by LG microwaves. A malfunctioning diode, responsible for converting AC to DC, can cause the machine to lose power. An electrically burning smell can indicate that the diode is faulty. It is critical to inspect the diode for any problems.

How to fix it:

A microwave diode replacement is simple and cost-effective. To do so, 

  • Disconnect the microwave from the power outlet, remove the glass tray and gliding roller, unscrew the screws attaching the venting and control panel,
  • Detach and lift it from the microwave, and remove the access panel. 
  • To avoid danger, use a multimeter to test the diode and discharge the capacitor’s stored electrical charge.
  • Remove the old diode and replace it by correctly connecting the ends and fixing them with screws. 
  • Replace all detached parts individually, securing them with screws. 
  • Plug the microwave back into the power socket to confirm it works correctly.

2. Magnetron fault

A microwave’s critical component, the magnetron, can become worn and damaged over time because the LG microwave uses high-voltage DC to heat food. The microwave stops heating if a magnetron is faulty. If the magnetron burns out, a replacement or new appliance may be required, which might be expensive, depending on the model.

How to Fix it

If your microwave oven is still under warranty, we advise replacing the worn magnetron, which will be a covered repair. However, if you have been using it for over five years, it is recommended to buy a new microwave as other components may start breaking down. To check if the magnetron is at fault:

  • Unplug the microwave and fully discharge the high-voltage capacitor for safety.
  • Touch one multimeter probe to the magnetron housing and the other to its terminal.
  • Remove all microwave parts and access the magnetron.
  • Unplug the wires from the magnetron and set the multimeter to the highest ohm setting.
  • To test the magnetron, touch one multimeter probe to its housing and the other to its terminal.
  • Check the reading. If it is greater than 1 ohm, replace the magnetron.

“It is best to seek professional help for this task. As replacing the magnetron is expensive, many recommend getting a new microwave.”

3. Faulty door switches

The LG microwave is not working but has power due to malfunctioning door switches. These safeguards prevent the appliance from operating if the door is left open, as microwave radiation can cause skin burns. The microwave usually comes with three or four door switches that help the door close properly and alert the appliance that it is safe to begin heating. A microwave won’t heat due to broken or malfunctioning components.

How to Troubleshoot:

  • Using a multimeter, check the continuity of each door switch to identify the malfunctioning microwave.
  • Replace the switches if the multimeter doesn’t emit a beeping sound. 
  • For 15 minutes, let the capacitor discharge. 
  • To reach the control panel and remove the grill from the microwave,
  • Unscrew the microwave top. Avoid causing any wire damage when removing the switch assembly.
  • To release the door switches, push the release tab. 
  • Wait 15 minutes after unplugging the microwave for the parts to discharge.
  • To loosen the grill, remove the screws on the microwave. 
  • Take out the broken door switch and control panel. 
  • Reassemble the microwave after installing the replacement door switch. It should take a few minutes to complete this.
  • Depending on the model of your LG microwave, buy replacement door switches. 
  • Reinstall each component and check the microwave’s heating ability. 

Related Posts:

4. Faulty High-Voltage Transformer

A microwave oven’s malfunctioning high-voltage transformer might result in food not heating, a burning odor, and sparks. It’s critical to cease using the microwave and swap out the transformer if this component breaks. The microwave does not heat food but runs at this point if the transformer that powers the magnetron is malfunctioning. However, using the microwave repeatedly could be dangerous.

How to Fix it:

  • Unplug the microwave oven’s high-voltage transformer and leave it to sit so all its parts can discharge before troubleshooting.
  • Disassemble the microwave, unplug it from the outlet, and connect a voltmeter to each terminal on each head. The transformer is OK if the reading ranges from 50 to 70. If not, swap it out.
  • Remove the glass tray and gliding rollers, unscrew the bottom panel, and tighten the mounting screws holding the grill in place.
  • Use needle-nose pliers to release stored power and return the microwave to its original position. Remove the fasteners and disconnect the six transformer wires.
  • Put the new transformer in its place, fasten it to the base, then swap out the old one.
  • Plug the microwave back in after reassembling the components.

Faulty High-Voltage Capacitor

A microwave oven’s capacitor gives the magnetron the high voltage it needs to operate correctly. It transforms the 120 volts from the wall outlet into the high voltage the magnetron requires to heat meals. The capacitor has a shelf life and could degrade. It doubles the voltage of the magnetron by converting the A/C current to the D/C current. The circuit will malfunction if the capacitor breaks down. Repeat the previous procedures to get to the capacitor. The magnetron is close to the capacitor.

Troubleshoot Guide:

  • Unplug the microwave.
  • After completely discharging the microwave, you can access the capacitor. Refer to the user handbook or guide for specific model locations, which vary for the capacitor.
  • With insulated metal pliers and a VOM meter, touch the heads to the capacitor’s terminal.
  • If the capacitor is defective, replace it.
  • Use a flat-tipped screwdriver or a pair of needle-nose pliers to remove the terminal screws.
  • Put on appropriate gloves and hold off releasing the capacitor for five seconds.
  • Reassemble the microwave after replacing the outdated capacitor.

6. Faulty Thermo protector

An essential part of a microwave that stops it from heating if it overheats is the thermoprotector. The microwave stops heating or won’t turn on if it trips. Use a multimeter to check for continuity to see if the thermoprotector is malfunctioning. If not, get a replacement. However, replacing electronic parts in a microwave is perilous due to the risk of electric shock. Only licensed technicians should replace the thermoprotector. Examine the black and burned fuses to see if the thermoprotector is at fault.

Troubleshoot Steps:

Follow these procedures to change a thermal fuse in an LG microwave:

  • Turn off the microwave’s power, then remove the screws holding the front vent in place.
  • Slide the grill covering the fuse location to the left and unscrew it.
  • Carefully remove the little cylinder-shaped object with the metal terminals on either end.
  • You can use a multimeter to check for electric flow in the thermal fuse. If the meter doesn’t show any change, it is necessary to replace the fuse.
  • Insert the fresh fuse and make sure it clicks into position.
  • Replace the front vent and grill.
  • Restart the microwave and check whether the heating works again.
  • Check the high-voltage capacitor for any issues if the fuse keeps blowing.

7. Child lock feature

If the microwave is not heating up when you press the “Start” pad, it may be due to the active “Child Lock” feature. This safety feature prevents children from playing with or locking control keys during cleaning. Deactivate the feature to restart the microwave. Turn off the Child Lock feature for the control panel to operate and for the appliance to heat up.

How to Fix Step by Step:

  • Press and hold the “START” button for 4 seconds to turn off the “Child Lock” feature on the LG microwave.
  • The lock icon, which looks like a “L,” will vanish.
  • After using the microwave again, it should be heated. 
  • If the microwave still doesn’t heat up after pushing the Start button, reset the appliance by turning it off, disconnecting it for three minutes, and restarting it.

8. Power supply issues

For LG microwaves to operate correctly, power must be reliable and sufficient. The microwave won’t heat due to power supply issues. Unsuitable wall outlets, damaged wall outlets, tripped circuit breakers, and poorly attached power cords are among the problems that can prevent the microwave from heating. The solution to these power issues depends on the precise reason:

  • A frayed power cord
  • A broken wall outlet
  • A tripped circuit breaker
  • An incorrect wall outlet

How to Fix Step by Step:

Follow the below methods to troubleshoot LG microwave power difficulties.

  • Ensure you firmly insert the power cord into the wall outlet. 
  • To confirm if the outlet is receiving power, try using another device with it. Continue with subsequent power problem checks if functional.
  • Check whether the microwave switch has tripped the circuit breaker and reset it. If you need help resetting or the issue keeps coming up, seek professional assistance. Flick the switch on and off to reset the circuit breaker without a tripped switch.
  • If the power source for your microwave is fused, check the fuse for damage and replace it as necessary.
  • If your microwave is not heating up despite being freshly used, ensure your wall socket can supply the microwave with the necessary electricity.
  • An LG microwave requires a dedicated 120V, 60Hz AC outlet with a 15-20 circuit breaker or fused power supply to protect it. A licensed electrician should inspect unsure outlets to ensure correct installation.

“Consider contacting LG’s repair service if these troubleshooting techniques don’t fix the microwave’s heating problem. Depending on the precise root of the issue, there are different approaches to solving LG microwave power problems.”

Related Posts:


The high voltage of the appliance makes it risky to replace internal parts in an LG microwave. Even if you believe you can perform some of the processes yourself, calling a certified specialist for testing and repair is advised. If your LG microwave is not heating food, it could be a faulty door switch, a burned-out diode, a lousy transformer, or a faulty capacitor. Wear gloves, let the microwave discharge, and take all other safety precautions before handling any of the microwave’s parts. Identifying and replacing the defective component is simple if you are familiar with appliances. If the problem continues, reach out to a professional repairer for help.

Frequently Asked Questions

 LG microwave does not heat food but runs; why?

Several factors might cause your LG microwave not to heat properly. These include issues with the power supply, faulty components like the magnetron, or problems with the door switches and safety features

 Why my microwave does not heat food but run? What might be the cause?

When your microwave runs without heating food, it could indicate problems with critical components like the magnetron, high-voltage diode, or capacitor. Additionally, malfunctioning door switches or thermal fuses might contribute to the issue.

What’s the primary factor leading to a non-functional microwave?

The most common reason for a microwave not working is a malfunctioning magnetron, which generates microwaves. Power supply components, door switches, and safety mechanisms can cause problems.

How can I adjust the settings on my LG microwave?

To regulate your LG microwave’s settings, consult the user manual for model-specific instructions. Generally, you’ll use the control panel to adjust cooking time, power levels, and other features to suit your cooking needs.

What’s the process for resetting my LG microwave?

To reset your LG microwave:
Unplug the microwave from the power source for a few minutes.
Reconnect the power and check if the microwave’s display resets.
If not, consult the user manual or contact LG support for model-specific reset instructions.

About the author

Author description olor sit amet, consectetur adipiscing elit. Sed pulvinar ligula augue, quis bibendum tellus scelerisque venenatis. Pellentesque porta nisi mi. In hac habitasse platea dictumst. Etiam risus elit, molestie 

Leave a Comment