Why Does Microwave Turn on When Door Opens? All You Need To Know

These home appliances we’ve got are really helpful, and I sometimes just imagine what life would’ve been like without them.

On some days, these same helpers become torn in our flesh. Especially when you’re done using the microwave and want it to turn off, it wouldn’t listen and heed your request.

This article will examine why the microwave still turns on when the door opens.

Normally, the microwave should turn off when the door is open, so why does my microwave turn on when the door opens? If your microwave refuses to turn off when the door is opened, there’s a fault with the door interlock switch.

The microwave is never normal to be still on when the door is opened. Undisputedly, the microwave oven is one of the most used kitchen appliances.

And as such, it turns out to act weird, becoming a bit frustrating. Especially when it’s not turning on at the time, it’s needed the most.

Imagine feeling so hungry in the middle of the night, and you try to reheat some food in the kitchen, and the microwave isn’t responding. Did you get that feeling? Lol.

What is Door Interlock Switch and its Purpose?

Door interlock switches are safety devices that check whether doors and other movable guards like fences and covers are opened or closed.

Their main work is to see that the machine or device it has been employed to doesn’t start up in an unsafe situation.

It also sees to it that the door of the device or machine can’t be opened or accessed while it’s running.

So this mechanism is employed on the microwave to turn it off when the door is opened.

So the moment the microwave remains on whiles the door is opened, then it means the door interlock switch is at fault and needs to be replaced.

When the microwave turns on whiles the microwave door is still opened and the power is on, it can also be associated with faulty interlock switches.

But it’s not always an interlock switch fault, as it can also be a fault on the side of the control board. But that isn’t what we will be looking out for.

Which Should I Go For, Repair or Replace Door Interlock Switch?

Before you can even think of repairing or replacing your alleged faulty door interlock switches, you might want to test to confirm they’re indeed faulty and the ones causing the microwave to turn whiles still the door is opened.

Testing Door Interlock Switch

Testing a microwave door interlock switch can be done with any variety of multimeter.

And before you start, you need to ensure the microwave is unplugged. Another thing to note about microwaves is that they can still hold a lethal electrical charge even in their unplugged state.

So to be on a much safer side, discharge the capacitor. After all this disconnection, you remove the microwave cabinet to have access to the interlock switches.

Remove the switches and test them for continuity. This test will determine if a continuous electrical path is present in the switch.

The analog and digital multimeter models will be used for the testing. With the analog model multimeter, before you start testing, rotate the range selection dial to the lowest setting for ohms of resistance, then calibrate the meter by pinching the probes together while adjusting the needle to read zero.

Same with the digital model, rotate the dial to the lowest setting for ohms of resistance.

Now let’s get to the testing of the interlock switches. You will find these three labels on the switch. That is, NC, NO, and COM, with each of them having a terminal.

So to test for your continuity, use your first probe to touch the COM terminal, and the second probe to touch the NO terminal.

After they’re all in place, actuate the switch, and look at the readings on your multimeter.

If the meter reading shows zero ohms resistance, then the switch has continuity. Meaning the switch is not defective.

Repeat the same test, but this time, it should be the COM and NC terminals. If any of the tests show there’s no continuity in the switch, then the switch has to be replaced.

Is it Bad if the Microwave Runs With the Door Open?

Just imagine the human being as the food, with the microwave radiations acting on it. I’m sure that will even answer this question for you.

It is very bad and dangerous for the microwave door to be opened whiles still running.

As we know, with microwave operation, the microwave radiation produced by the magnetron, when absorbed by the food in it, acts on water molecules.

And the human body also has some water content in it. So when the door is opened while the microwave runs, microwave radiation will be produced and absorbed by the human body.

The absorbed radiation will try to react with the human body and vibrate the water molecules in any nearby human being, which will be very dangerous to human health.

Also, some sensitive parts of the body, like the eye, cannot withstand this kind of intense heat. And when that continues, it will end up damaging such parts.

How do I Know if my Microwave Door Switch is Bad?

What is making you insinuate that your microwave door is defective? Does it still run even when the door is opened?

Or does it turn off while the door is closed and the power is still on? Either of the above scenarios indicates a faulty part of the microwave, not the door entirely but the door interlock switches.

These switches can be repaired, but it will be good for you if you can replace them.

And to be so sure whether it is indeed faulty and needs replacement, you can follow the instructions above or watch the attached video to know how you can test to know if it’s defective.

But in most cases, we concluded the door interlock switches to be faulty when it turns on whiles the door is opened. And also, when turns off when the door is closed, and power is still in it.


When your find your microwave to be still on when the door is opened, then the door interlock switch, which is a safety device employed on microwaves to make sure the door is not opened when the device is still running, and also to trigger the device to turn when the device is opened is at fault and needs replacement.

You need not postpone the replacement as the microwave radiation produced by the magnetron of the microwave is not good for the human body.

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