A microwave is an essential appliance in your kitchen. It makes the food very easy and saves time in your cooking. But every home appliance comes with its drawbacks. Sometimes the microwave can turn on automatically when the door opens.
The most common reason why the microwave turns on when the door opens is a faulty door. It could happen due to a faulty door latch or interlock switch. A faulty control panel and bad wiring can also cause the microwave to turn on when the door opens. Replace/fix the faulty part to fix the issue.
In this article, I will go deep down into why your microwave turns on when the door opens, and I will also discuss the solutions. So, keep reading.
Why does my microwave turn on when the door opens?
These are the common reasons your microwave turns on when you open the door:
1. It is designed that way.
Nowadays, microwaves come with the latest design and the inbuilt method that when you open the door, the microwave’s light automatically turns on.
So the users can look inside the microwave.
But if the fan also turns on with the light, it is not by design.
There can be a problem with the internal system of the microwave.
2. The interlock switches are stuck
There are 2-3 interlock switches inside a microwave.
The switches maintain the operation of the microwave.
If the switch is pressed, it ensures the microwave is running.
After pressing, they can return to the normal position, but if the switches are stuck, the microwave keeps running.
It can be why your microwave turns on when the door opens.
3. Faulty door interlock switch
A faulty door interlock switch also can cause the turning on of a microwave when the door is opened.
The door of the microwave is attached to the door bar.
And on the door bar, there is an interlock switch.
The interlock switch has metal prongs that send the signal to the door control panel, and the door control panel controls the movement of the motor.
If the door latches or the interlock switch is faulty, it can turn the microwave on when the door is opened.
4. Problems with the control panel
The control panel controls the whole system of the microwave. It passes the signals to motors to stop or run its function.
If the control board is faulty, then it stops working. Then this can be a big reason why the microwave turns on when the door opens.
How to fix your microwave that turns on when the door opens?
Here are the steps to fix your microwave:
1. Reset your microwave
Modern microwaves have inbuilt software to control the system.
Sometimes software shows a glitch in a microwave, or the button can be frozen due to weather.
This can cause the microwave to turn on when you open the door.
To reset the microwave, you need to follow the below steps.
There are two types of reset methods for a microwave.
The 1st one is a soft reset, and the 2nd one is a hard reset.
- First, find the reset button on your microwave.
- Press the button and check whether you can find any beep sound. Some microwave displays can show a lock icon when you press the button. The reset button presents in different positions in the different models per the interfaces. So you must check the manual where your reset button is presented on your model.
- Once you have seen the lock icon, proceed to the next step.
- Press and hold the reset button for 3 seconds to turn off the child lock feature of your microwave.
- Now open the microwave door and check if it turns the microwave on.
- If the problem is not resolved completely, you must hard reset it.
- Find the power cord. The power cord brings power from the microwave power supply to the electric power outlet on your home wall.
- Now unplug the microwave plug from the power outlet. For safety, try to use a rubber glove on your hand, then unplug the microwave’s plug.
- Now sit the microwave in a smooth place and keep it unplugged for 30 minutes for full discharge.
- Now plug in the microwave like other appliances.
- Open the microwave door and check if it is still turning on when you are opening the door.
2. Fix the control board
Sometimes the control panel cannot lead the signal from the panel to the motor, which is why it starts malfunctioning.
To fix the control panel, follow the below steps:
- First, unplug the microwave from the power source.
- Now open the microwave door and unscrew all the screws on the upper side of the microwave.
- Now remove the cabinet to get access to the control board. The control board is located behind the keypad.
- Before getting access to the control board, you can find a screw holding the keypad in the panel.
- Now unscrew the screw.
- Once you get the screw out, hold the panel, lift it up, and come out for you.
- When you do this, you can find wires behind the panel. You need to unplug the wires.
- Now you can find the control board behind the keypad. Pull out the board from the panel.
- To do this, you should first unscrew the 4 screws in the four corners of the panel using a screwdriver.
- Remove the electronic strips by pulling them up.
- Now you can find that the board has come out.
- Check if you can find any burnout or damage on the control board. You should replace the control board if you find any damage and burnout.
- If you do not find any damage, you must test the board with a multimeter to find continuity.
- You must set the multimeter to Rx1 and place the probes on the output terminals. If you find no continuity, you must replace the control board.
- Once you pull out the control board from the panel, replace it with the new one. Screw the nuts with a screwdriver and set the strips again.
- Once the panel is ready, reinstall the wires and fix the control panel properly.
- Now plug it in and check if the problem is resolved.
Check if you still find the microwave turns on when you open the door or not.
3. Fix the faulty door interlock switch
The microwave door has interlock switches that send signals to the motor through the control board.
If the switch or switches are damaged or broken, it starts malfunctioning.
To fix the door interlock switch, follow the steps below:
- The first and most important step, unplug the microwave from the power source.
- Remove the screws from the upper side of the microwave. There can be 2 or 4 screws based on the model.
- Once the screws are removed, slide the upper panel left or right and pull it out.
- Now open the door of the microwave and remove the control panel.
- To remove the control panel, you need to remove the screws. One is located upside the panel, and the other is behind the control panel. Make sure you hold the panel with one hand when removing the screws. Otherwise, the panel can fall.
- Once it is done, remove the panel by sliding it up.
- Once the control panel is released, you will find a series of connections you need to remove them. Always take a picture of these connections so you can fix them next time.
- Once you remove the control panel and the series of connections, you can find an empty cabin with wires and switches on a switch assembly.
- Now you have to remove the switch assembly that holds all the switches. To do that, you must remove the screws, one on the top and one on the bottom.
- Once you remove the screws, you can find the switch assembly hanging. To remove the assembly, you need to slide it up and then toward the back and bring it out of the cabin.
- When you bring out the assembly, you can find different connections. Each microswitch has two connectors that you need to remove. Make sure you take a picture so you can reassemble it easily. Now remove the connectors.
- Once you get the switch assembly, you must diagnose it to check which switch or switches are faulty. To do that, you need a multimeter, and you need to check the continuity. The continuity test checks the current flow inside a circuit. If the current flow is not happening, the circuit is open and damaged or has high resistance because a closed circuit is passed in the continuity test.
- If you look at the diagram on the side of the switches, it tells that the switches are not always open, meaning when the button on the switch is not depressed, it won’t allow the electricity to flow. And if the switch button is closed, it allows electricity flow.
- So, now put the multimeter on continuity, take an alligator clip on lead and test the switch. If the switch is open but allows current to flow, then it is a faulty switch, and if the switch is corroded, you also need to replace it.
- To find out the faulty switch and the reason behind it, you need to replace it.
- To do that, you have to remove the switch from the switch assembly.
- Push down the little tab inside the switch so you can swing the switch out of the way and lift it up. If you want to repair the switch instead of replacing it, follow the steps.
- Take a knife or any blunt object, press it into the switch’s seam, and take the switch’s body apart. Be careful. There are many little parts inside, don’t lose them.
- Once you open the switch, gently remove the top part of it, and thus it exposes the internals of the switch. And now you can see how it works as we press a button. Now push the switch contacts separately and open up. release the switch so that the contact is open.
- Often, these little microswitches have a micro connector, which can rust over time and become closed. So you must clean the area by taking a small nail file. You have to take the file between the connector and clean their surface.
- You must push the button to open up those connectors. Take the nail file and gently go inside and clean it. Now you can see the switch is working properly.
- Once cleaning is done, retest the switches and check if you can get continuity. If you get the continuity, reinstall the switch inside the assembly.
- Now reinstall all the parts of the microwave and check if the issue is resolved or not.
You can now understand why your microwave turns on when the door opens. You need to find out the parts that are damaged and have become faulty and fix them by going through the steps I have mentioned in the article.
As the microwave is an electrical appliance, you need to be cautious when you handle it. And if you can not fix the problem on your own, then you should call the technician.
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Reference: Samsung microwave error code official guide, Whirlpool Official Manual, Whirlpool Troubleshooting, LG Official Microwave manual, LG Microwave Reset.