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Microwave not heating
Common reasons your microwave not heating
The most common reasons your microwave is not heating are a bad thermostat, malfunctioning electronic control board or a broken switch.
53% of the time it's the Thermostat
23% of the time it's the Electronic Control Board
15% of the time it's the Switch
9% of the time it's the Something else
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Common microwave repair parts you may need
Replacing one of these microwave parts may fix your problem.
Thermostat Replacement
A defective thermostat in a microwave can lead to various issues, particularly affecting the power supply to the microwave's components. Microwaves typically feature multiple internal thermostats designed to safeguard users in the event of component failure. For instance, many microwaves include a magnetron thermostat, which triggers in response to excessive current or temperature in the magnetron region of the microwave cavity. Additionally, another thermostat oversees the cooking cavity temperature, activating when temperatures reach unsafe levels. If any of these thermostats trip, the microwave will fail to operate, resulting in non-functional lights, fans, and display. Given that microwaves contain high-voltage components such as transformers and capacitors that retain dangerous electricity even when unplugged, it is advisable to have a Sears Home Services professional assess and repair the microwave.
Electronic Control Board Replacement
When a microwave's electronic control board malfunctions, it can result in various issues, such as power or heating failures, or it may prevent the microwave from shutting off. This is because the control board acts as the central control hub of the microwave, overseeing critical functions like heating via the magnetron, operation of cooling fans and lights, rotation of the turntable motor, setting cooking times and power levels, and displaying information. When the electronic control board malfunctions, it can disrupt communication among multiple components, potentially leading to further problems. A malfunctioning board might also produce unusual sounds like chattering or clicking, or emit a burning odor. Considering the potential impact on various microwave functions, it is recommended to have a Sears Home Services professional conduct diagnostic tests on the board to determine if replacement is necessary.
Switch Replacement
A malfunctioning switch in a microwave can lead to various issues, particularly affecting the power supply to the microwave's components. Microwaves are equipped with internal thermal switches and interlock switches designed to safeguard users in case of internal component failures. Door interlock switches, for instance, prevent the microwave from operating when the door is open to avoid exposure to harmful radiation. Additionally, many microwaves feature a magnetron thermal switch that activates if it detects excessive current or temperature in the magnetron area, as well as another thermal switch that monitors cooking cavity temperature and activates during high-temperature conditions. Should any of these switches fail, the microwave may fail to start, and its lights, fans, and display may cease to function. Given that microwaves contain components like high-voltage transformers and capacitors that can retain dangerous levels of electricity even when unplugged, it is prudent to have a Sears Home Services professional inspect and repair the microwave.
What to expect when you experience a microwave not heating issue
How do I fix the not heating problem?
Addressing most issues with heating typically entails replacing the thermostat, electronic control board, or switch. However, since there are numerous possible causes, conducting a comprehensive diagnosis is crucial to resolving the problem effectively. An accurate diagnosis is essential for determining the extent of the repair needed.
Sears Home Services advice for a microwave that is not heating
When the microwave fails to heat up, it could be due to various reasons. To prevent unnecessary part replacements, we suggest having a Sears Home Services expert conduct diagnostic tests to pinpoint the underlying issue. Our technicians possess extensive experience in diagnosing all kinds of microwave malfunctions.
What to be aware of for a microwave not heating diagnosis
Diagnosing issues with modern appliances can pose challenges without adequate knowledge and training. Attempting repairs without employing proper diagnostic techniques often leads to a trial-and-error approach of replacing parts. In the last decade, appliances have evolved significantly, with many incorporating complex electronic components that are challenging to assess. As a result, do-it-yourself repairs on contemporary appliance models are progressively more complicated.
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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 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 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 magnetron is a component in microwave ovens that generates the microwaves used to cook food.