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

Did your microwave turn when you opened the door without pressing the “start” button or setting a timer? This can be extremely dangerous, 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.

Your microwave turns on when you open the door because of a normal feature, a firmware glitch, a faulty door switch, or faulty internal circuitry. You can reset the device, do a quick break routine, replace the faulty door switch, or call a technician to fix the issue.

In this article, I’ll discuss why your microwave automatically turns on when you open the door. Some reasons are harmless, while others present a potential radiation hazard. I’ve provided a detailed guide on fixing your microwave so it doesn’t turn on when the doors open.

Reasons Why Your Microwave Turns On When the Door Opens

There are 4 common reasons why your microwave turns on when the door opens:

  1. It’s by design
  2. Malfunctioning door switch 
  3. Firmware glitch
  4. Faulty internal circuitry

Let’s go over each of these points in more detail so you can better understand how opening the microwave door can turn on the appliance. 

1. It’s by Design

If the only thing that happens when you open the door is that the lights turn on, then you’re looking at a perfectly normal feature.

Many manufacturers program their microwave ovens to turn on the lights when the door is opened. This allows users to see what’s inside the oven—a convenient feature, especially when retrieving something hot from the oven in a poorly lit environment.

However, it’s only a normal manufacturer-provided feature when just the lights go on. 

If the microwave fans turn on along with the heating, and you see the tray spinning as soon as you open the door, that is definitely not a built-in feature. On the contrary, it indicates something is wrong with your microwave, either with the sensors, the circuitry, or internal software, and you should get it checked out.

2. Malfunctioning Door Switch 

Modern microwaves have built-in safety mechanisms that stop them from working when the door is open. However, if these mechanisms fail or malfunction, the opposite can happen, and your microwave could automatically turn on when you open the door.

Your microwave oven has 3 or 4 door switches—also known as interlock switches—located behind the bracket near the door latch. You won’t be able to see them unless you disassemble the oven, but they’re there.

The purpose of these switches is to signal the motor when the door is opened or closed. On the other hand, the motor is configured only to turn on when it gets the signal the door is closed and will instantly turn off if the door is opened.

However, if one or more of the interlock switches aren’t working, the motor might not know what state the door is currently in—open or closed. As a result, the motor might start when you open the door.

3. Firmware Glitch

Modern microwaves have become increasingly sophisticated, and many are coming with automation features to make our lives more convenient. 

Many new models have a central control board that accepts signals from the different sensors, analyzes them, and tells other components to take the appropriate action. Now, if there’s a glitch somewhere in this system, then your microwave can malfunction and start to behave oddly.

For instance, there might be a firmware in charge of turning the motor on and off depending on whether the door is closed or open. However, a glitch could cause this feature to malfunction and turn on the microwave when the doors open.

4. Faulty Internal Circuitry

A microwave oven might seem like a simple kitchen appliance, comparable in function to a toaster oven. However, it’s much more complicated on the inside, using a lot of high-end electronics.

Yes, all a microwave does is heat your food, but it’s doing that using microwave radiation. It has a magnetron inside it, which creates the radiation. Since microwaves are harmful to humans and electronic equipment, the oven boasts tons of security features and fail-safes to ensure it doesn’t pose a radiation hazard.

As you can imagine, a microwave oven has a lot of internal circuitry. If something goes wrong, like issues with the wiring or water in the motor, it can cause the oven to automatically turn on when the door is opened and turn off when the door is closed.

Dangers of a Microwave That Turns On When the Door Opens

Is it dangerous if a microwave oven turns on when you open the door?

Probably not, but sometimes it can be! It all depends on what you mean by your microwave “turning on”.

If the microwave oven only turns on the lights when you open the door, it’s nothing to worry about. If the tray starts spinning and the fans go on, but the heating stays off, it signals something is wrong, but it’s still nothing dangerous.

However, if the microwave oven starts heating when you open the door, it’s dangerous and poses a radiation hazard. 

Your microwave oven heats food using microwave radiation. If it reaches your body, it will start heating the water content in your cells, causing burns and even tissue damage. 

What’s worse, the dangerous effects of microwave radiation only show after some time has passed from when you were exposed. This means you could open the microwave oven and receive dangerous levels of radiation without feeling anything then and there.

Other than this, microwave rays can also damage other electronic appliances in their vicinity.

So this brings the question: how do you know if the oven is radiating microwaves when the door is open?

Well, a simple test would be to take a cup of water, place it inside the oven, and close the door to a slit, so it’s not fully closed. If the water gets warm after a minute or two, it means the oven is heating when the door is open, making it a radiation hazard.

What To Do if a Microwave Turns On When the Door Opens?

Here are 5 things to do if a microwave turns on when the door opens:

  1. Do a soft reset.
  2. Perform a quick break routine.
  3. Do a hard reset.
  4. Replace the faulty door switch.
  5. Call a technician.

Let’s discuss these points in more detail. By the end, you’ll be better equipped to handle what could be a dangerous situation.

1. Do a Soft Reset

If you believe your microwave is turning on when you open the door because of a firmware glitch, doing a soft reset should fix the issue. It’s also the simplest potential fix you can try, so why not start with that?

Most microwave ovens should have a “RESET” button on the display board, and pressing it should do the trick.

That said, if your microwave doesn’t have a RESET switch, don’t panic. Some models hide the reset functionality, so users don’t accidentally reset their system. 

Try to press and hold the “OFF” button or “CLEAR” button on your microwave for 3-5 seconds. You should hear a beep and a message on the display board confirming the device has been successfully reset to the factory default settings.

However, if that also doesn’t work, check the user manual on resetting your microwave oven, and follow the manufacturer specified steps.

2. Perform a Quick Break Routine

If doing a soft reset doesn’t work, you can try doing a quick break routine. This can help correct problems or glitches with the microwave sensors, in case that’s what’s turning on the device when you open the door.

Here’s a simple guide on how to do a quick break routine:

  1. Take a small cup and fill it with a mix of salt, sugar, and water. 
  2. Place the cup inside the microwave.
  3. Put the microwave on low and set the timer for 30 seconds.
  4. Let the microwave do its thing until 30 seconds are up.
  5. Press the “STOP” or “CLEAR” button on the microwave. Don’t take out the cup before you press that button.
  6. Take the cup of water out.

If the microwave oven didn’t start when you opened the door, then you fixed the issue. If it persists, it’s time to try other troubleshooting techniques.

3. Do a Hard Reset

Sometimes a soft reset isn’t enough to clear out stubborn firmware errors and glitches. In that case, you need to perform a hard reset.

Unfortunately, you can’t hard reset a microwave by conveniently pressing a button. 

You’ll need to unplug the device and let it sit for a while, from 30 minutes to an hour. You need to wait this long so that the electricity inside the microwave’s processors and circuits have time to dissipate.

Once the time has passed, plug in the microwave and turn it on. If the issue comes from a software glitch, this should fix it.

4. Replace the Faulty Door Switch

If a faulty door switch is causing the microwave to turn each time you open the door, you can easily fix the issue by replacing it with a new, working door switch.

Of course, you can call a technician to help you with this, especially if the microwave still has a warranty. However, it’s a straightforward DIY fix, and you should be able to do it on your own if you follow these steps:

  1. Turn off and unplug your microwave oven. Since you’ll be dealing with wires and electrical components, you should ensure the device is not connected to any power source.
  2. Remove the display board or keypad. You can consult the microwave’s user manual to know which screws to remove. With most microwaves, you’ll need to remove the screws holding the upper cabinet. After removing the upper cabinet, you’ll find screws that hold the keypad. Remove the screws and slide out the display board.
  3. Locate the switch assembly and take it out. The interlock switches are all mounted on a switch assembly behind the door latch. You should be able to access it after removing the display board. Usually, you’ll be able to take it out by hand. However, in some models, they’ll be mounted using screws, in which case you’ll need to remove them first.
  4. Remove the interlock switches and test them. To test the switches, just press them and see if they are making a clicking sound. You’ll need to replace the switch if you don’t hear a clicking sound.
  5. Replace the faulty interlock switch with a new one. Note down the model number of the defective switch. When buying the replacement part, make sure the model number matches, or else it won’t work with your microwave.
  6. Put everything back in order. After installing the replacement interlock switch, re-mount the switch assembly to its usual position, reattach the display board, and finish up by covering everything with the upper cabinet.

This should fix your microwave oven from turning on when you open the door. But if it persists, the issue likely stems from a deeper problem.

5. Call a Technician

If resetting the microwave and changing the interlock switch didn’t help solve the problem, it’s likely that some of the internal components are malfunctioning. 

Problems with the wiring or getting water inside the motor can cause your microwave to turn on when the door opens.

However, I’d strongly advise against tinkering with your microwave’s internals yourself. It’s worth noting that a microwave is a high voltage device and also a radiation generator. If something goes wrong, you’re at risk of both: a shock hazard and a radiation hazard.

In this case, it’s better to call a qualified and professional technician to troubleshoot your microwave.

Key Takeaways

If your microwave oven simply turns on the lights when you open the door, it’s likely an in-built feature, and there’s nothing to worry about.

However, if the microwave oven turns on the fans and the tray starts spinning as soon as you open the door, something is wrong with the sensors, firmware, or internal circuitry. The device can become a health hazard if it also starts heating once you open the door.

To fix this, you can try resetting your microwave, doing a quick break routine, replacing the faulty door switch, or calling a technician for help.