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LG microwave no heat
Common reasons your LG microwave has no heat
The most common reasons your LG microwave has no heat are a bad thermostat, malfunctioning electronic control board or a broken switch.
42% of the time it's the Thermostat
23% of the time it's the Electronic Control Board
6% of the time it's the Switch
29% of the time it's the Something else
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Most common repairs needed to fix a LG microwave
Thermostat Replacement
A bad thermostat in a microwave will cause a variety of issues, mainly with power to the components of the microwave. Microwaves have several internal thermostats that protect you from harm when components inside the microwave fail. Many microwaves have a magnetron thermostat that trips when it detects high current going to the magnetron or high temperature in that area of the microwave cavity. Another thermostat monitors the temperature of the cooking cavity and trips when high temperatures occur. If any of these thermostats trip, the microwave won’t start, lights and fans will be inoperative and the display will be blank. Because microwaves contain a high-voltage transformer and high-voltage capacitors that retain a lethal amount of electricity even with the microwave unplugged, a Sears Home Services professional should examine the microwave and perform the repair.
Electronic Control Board Replacement
If a microwave electronic control board is malfunctioning, it can lead to various failures in the microwave, including a lack of power or heating, or it could prevent the microwave from turning off. This is because the board serves as the brain of the microwave, controlling crucial components such as magnetron the heats food, cooling fans, lights, the turn-table motor, cooking times and power level settings and the display. If the electronic control board malfunctions, it can disrupt communication between many different components. A failing board may cause a chattering or clicking noise or emit a burning odor. Due to the potential impact on multiple components, it is advisable to have a Sears Home Services professional conduct diagnostic tests on the board to confirm if replacement is necessary.
Switch Replacement
A broken switch in a microwave will cause a variety of issues, mainly with power to the components of the microwave. Microwaves have several internal thermal switches and interlock switches that protect you when components inside the microwave fail. Door interlock switches prevent the microwave from running when the door is open so you aren’t exposed to harmful radiation. Many microwaves have a magnetron thermal switch that trips when it detects high current going to the magnetron or high temperature in that area of the microwave cavity. Another thermal switch monitors the temperature of the cooking cavity and trips when high temperatures occur. If any of these switches fail, the microwave won’t start, lights and fans will be inoperative and the display will be blank. Because microwaves contain a high-voltage transformer and high-voltage capacitors that retain a lethal amount of electricity even with the microwave unplugged, a Sears Home Services professional should examine the microwave and perform the repair.
What to expect when you experience an LG microwave no heat issue
How is the no heat problem fixed?
Correcting most no heat problems usually involves replacing the thermostat, electronic control board or switch. However, there are many potential causes, so a thorough diagnosis is key to fixing the problem. An accurate diagnosis is essential to understanding how much the repair will be.
Sears Home Services recommendations for a microwave that won't heat
When the microwave has no heat it can be for many reasons. To avoid replacing unneeded parts we recommend having a Sears Home Services professional perform diagnostic tests to identify the root cause of the problem. Our technicians are experienced at diagnosing all types of microwave failures.
What to look out for with a microwave no heat diagnosis
Diagnosing modern appliances without proper knowledge and training can be difficult. Without using proper diagnostic techniques, fixing your microwave problem will only be achieved through changing parts on a hunch. Appliances, especially in the last 10 years, have become extremely advanced, and many models have electronic parts that are difficult to test. DIY repairs on the latest appliance models are becoming increasingly difficult.
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Michael C offered an excellent service
5 stars!!! Michael was quick and knowledgeable! Very accommodating and professional
Andreina G, Naples, FL
microwave
Mark really went over the microwave trying to fix it, this was his second time here for the same problem. August till ? till we get it replaced. we appreciate him for his knowledge of his job. thank you Mark
H M, Cadiz, OH
Customer
Mr. David is very polite and intelligent gentlemen. He came to replace a part on my microwave and he checked the microwave to make sure it was working properly. Mr. David gave me a courtesy call that he will be arriving in 15mins. He arrived on time for the appointment and took care of his job duties. Thanks Mr. David for all the hard work you do at Sears. Keep up all the good work.
Pamela W, Baltimore, MD
Frequently Asked Questions
Repair Microwave Resources
Discover the top causes of microwave malfunctions in 2025 with Sears Home Services.
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Learn how a convection microwave oven works and how to maintain it.
Is it worth repairing a microwave? Find out the pros and cons of repairing your microwave at Sears Home Services.
Glossary Terms
A microwave waveguide cover is a small, often mica or plastic piece inside the microwave that covers the opening where microwaves enter the cooking chamber, protecting the microwave's internal components from food splatter and ensuring efficient distribution of the microwaves.
A microwave diode is an electrical component that allows current to flow in one direction only, playing a crucial role in converting incoming electrical power into the microwave energy that cooks the food.
A microwave sensor is a technologically advanced feature in modern microwave ovens that measures vapor (steam) emitted by the food, adjusting the cooking time and power levels automatically for optimal results.
A microwave magnetron is a component in microwave ovens that generates the microwaves used to cook food.