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Why Does Your Microwave Turn On When You Open the Door?

If your microwave oven turns on when you open the door, the problem probably lies with a defective microwave door, a firmware glitch, a faulty internal circuit, or heat-sensitive switches. Don’t ignore this problem because it can be, as harmful microwave radiation spreads from the device and affects everything nearby. To fix the issue, you must first figure out why it’s happening and troubleshoot it accordingly.

Gadget Review reported that 90% of the time if your microwave keeps running when the door is open, the problem is certainly with the door interlock switch.

In some models, just like mine, the light automatically turns on when I open the oven door, but my oven doesn’t turn on and heats up immediately. But there was this one time that it happened, and I panicked. After thinking about what was wrong with my microwave, I finally realized that the microwave door needed to be replaced immediately.

This article will walk you through five of the most common reasons why your microwave oven automatically turns on when you open the door. Aside from the reasons, this article will also provide you with the dangers of this issue and what you can do about it. 

5 Reasons Why Your Microwave Turns on When the Door Opens

Here are five common reasons why your microwave turns on as you open the door:

  • It’s part of the design.
  • Faulty door switch.
  • Firmware glitch.
  • Faulty internal circuit.

Let’s look at these possible reasons in detail so you can fully understand why opening your microwave door activates your appliance. 

Part of the Design

It is normal if the lights turn on as the door opens. This is a useful function, especially in low-light situations, because it lets the user see what’s cooking in the oven.

However, if the microwave’s fans kick on simultaneously with the heating and you can see the tray spinning as soon as you open the door, there’s definitely a problem. It is a major red flag that there is a problem with your microwave’s sensors, electronics, or internal software, and it has to be looked at thoroughly by a professional.

Defective Door Switch

A modern microwave door will automatically disable the appliance if it detects that it has been left open. When these safety features don’t work as they should, the microwave will automatically turn on when you open the door.

There are three or four door switches (or interlock switches) on your microwave oven, and they’re hidden under the bracket by the door latch. You won’t be able to see them unless you disassemble the oven.

The switches detect when the door is open or closed and provide a signal to the motor. However, the motor will immediately shut off if the door is opened. It is set to activate only when it receives a signal that the door is closed.

If any of the interlock switches fail to function, the motor may be unable to determine whether the door is open or closed. That’s why the engine can fire up whenever the door is opened.

Firmware Glitch

Modern microwaves have become more sophisticated, and many now have automated functions to make our lives easier. 

Many new models have a central control board that collects signals from various sensors, analyzes them, and instructs other components to perform the required action. If there is a defect somewhere in this system, your microwave may malfunction and begin to behave strangely.

For example, firmware may be in charge of turning the motor on and off based on whether the door is closed or open. However, a glitch might cause this malfunction and turn on the microwave when the doors open.

Damaged Internal Circuit

A microwave oven may appear to be a basic household appliance, similar to a toaster oven in functionality. On the inside, though, it is far more complicated, utilizing a lot of high-end electronics.

It is true that a microwave heats your food, but it does it utilizing microwave radiation. It has a magnetron, which generates radiation. Since microwaves are hazardous to humans and electronic equipment, the oven has several security systems and fail-safes to guarantee that it is not a radiation threat.

As you might expect, a microwave oven has many internal circuits. If something goes wrong, such as faulty wiring or water in the motor, the oven may automatically switch on when the door is opened and off when the door is closed.

Is There Any Danger when Your Microwave Turns On As You Open the Door?

The Short Answer Is no. But we need to qualify that no. 

It’s not a problem if the only thing that turns on as you open your microwave door is the lighting bulb. However, if the tray begins to spin and the fans turn on, but the heating remains off, it indicates something is amiss, although it is not harmful. It is best to have it checked by a skilled technician.

Microwave radiation is used to heat food. If the radiation enters your body, it will heat the water in your cells, resulting in burns and tissue damage. 

If the microwave oven begins to heat up as you open the door, it is unsafe because it creates a radiation risk. The harmful consequences of microwave radiation only become apparent after some time has elapsed since you were exposed. This implies that you may open the microwave oven and be exposed to deadly quantities of radiation without feeling anything at first. 

Aside from that, microwave waves can harm other electrical devices near them. It is better not to place your microwave near or beside a refrigerator. A microwave produces a lot of heat, and putting it close to a fridge may interfere with its temperature regulation capacity.

The real question is, how do you know if the oven emits radiation when the door opens?

An easy test would be to set a cup of water inside the oven and close the door to a slit so it’s not completely closed. If the water becomes warm after a minute or two, it indicates that the oven is heating while the door is open, posing a radiation risk. If this happens, you must contact your manufacturer or a technician immediately.

What Should You Do If a Microwave Turns On When the Door Is Opened?

Here are five simple things you can do if a microwave turns on when the door opens:

  • Perform a soft reset
  • Do a quick break routine
  • Perform a hard reset
  • Remove and replace the faulty door switch
  • Seek professional help

Let’s take a closer look at these solutions one-by-one.

Perform a Soft Reset

If your microwave turns on when you open the door due to a firmware malfunction, a soft reset should resolve the problem. It’s also the simplest probable solution you can try at home. Most microwave ovens feature a “RESET” button on the display board. 

If your microwave lacks a RESET button. Some versions conceal the reset button so users do not accidentally reset their systems. Alternatively, hold the “OFF” or “CLEAR” button on your microwave for 3-5 seconds. You should hear a beep and see a message on the display board verifying that the device has been successfully reset to factory default settings.

If this doesn’t work, consult your microwave oven’s user manual and follow the manufacturer’s instructions.

Do a Quick Break Routine

You can do a brief break routine if a soft reset does not work. This can assist in resolving issues or faults with the microwave sensors if that is what is turning on the appliance when you open the door.

Here’s a little tutorial on conducting a fast break routine:

  1. Fill a small cup halfway with salt, sugar, and water. 
  2. Insert the cup into the microwave.
  3. Set the microwave to low and timer for 30 seconds.
  4. Allow the microwave to do its job for 30 seconds.
  5. Press the “STOP” or “CLEAR” button in the microwave. Do not remove the cup before pressing the button.
  6. Remove the cup of water.

You’re good to go if the microwave oven didn’t turn on when you opened the door. However, if it still doesn’t, it’s time to try other troubleshooting techniques to solve this issue.

Time for a Hard Reset

A soft reset isn’t always enough to remove persistent firmware faults and issues. In this case, a hard reset is required.

Unfortunately, a microwave cannot be hard reset by just hitting a button. You must disconnect it and leave it for 30 minutes to an hour. This time is required to dissipate the electricity inside the microwave’s processors and circuits.

After the timer has expired, plug the microwave and turn it on. If a software fault causes the problem, this should resolve it.

Replacing a Faulty Oven Door Switch

If a malfunctioning door switch is causing the microwave to turn on every time you open it, replace it with a new, functional door switch.

You may call a professional if the microwave is still under warranty. However, it’s a simple DIY fix that you should be able to complete on your own if you follow these steps:

  1. Turn off your microwave oven and unplug it. Since you’ll be working with wiring and electrical components, ensure it is unplugged from any power source.
  2. Remove the keypad or display board. To determine which screws to remove, examine the microwave’s user manual. Most microwaves need you to remove the screws that keep the upper cabinet in place. After removing the upper cabinet, look for the screws that keep the keypad in place. Slide out the display board after removing the screws.
  3. Locate and remove the switch assembly. All interlock switches are positioned on a switch assembly beneath the door latch. After removing the display board, you should be able to get to it. You can take it out by hand most of the time. However, in other versions, they will be attached with screws, which must be removed first.
  4. Remove and test the interlock switches. To test the switches, push them and listen for a clicking sound. If you don’t hear a clicking sound, the switch has to be replaced.
  5. Install a new interlock switch to replace the defective one. Make a note of the model number of the faulty switch. The new part will not function with your microwave if the model number does not match.
  6. Put everything back in its place. Remount the switch assembly to its original position after installing the replacement interlock switch, reconnect the display board, and finish by covering everything with the upper cabinet.

This should prevent your microwave from turning on whenever you open the door. If the problem persists, it is most likely the result of a larger problem.

Contact a Professional Technician

If resetting the microwave and replacing the interlock switch didn’t help, some internal components may be at fault.

When the door opens, your microwave may switch on due to electrical issues or water entering inside the motor.

However, avoiding messing with your microwave’s internals is strongly advised. It’s important to remember that a microwave is both a high-voltage appliance and a radiation generator. You might be exposed to shock and radioactive exposure if something goes wrong.

In this instance, calling a skilled and experienced technician to troubleshoot your microwave is the best solution.

Conclusion

If opening your microwave door causes the lights to turn on, this is an inbuilt feature and nothing to worry about. However, if something is amiss with the microwave’s sensors, firmware, or internal circuitry, the fans will start spinning as soon as the door is opened. 

If the microwave begins heating when you open the door, it poses a potential health risk. Try to do a soft reset on your appliance. In case this doesn’t work, call a professional technician to do the job and protect yourself from any possible risk, there is. 

It’s understandable that we often avoid calling for professional help and trying to fix the problem ourselves. However, a microwave oven can pose a radiation risk that can harm you and your family.

It’s better to contact your manufacturer or any knowledgeable technician to do the job for you.

Author

  • Hunter Hayes

    Hunter Hayes is a seasoned wordsmith with an obsession for all things related to Home Improvement. With years of experience in the subject, he brings to TemperatureMaster.com a unique blend of technical understanding and approachable writing. Hunter's articles not only explain complex thermodynamic ideas, but they also provide practical advice for day-to-day temperature management. Hunter's intelligent contributions will keep you well-informed and comfortable in every circumstance, whether you're intrigued about climate science or looking for help on optimising your home's HVAC system.

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