Microwave Turns On When the Door Opens?

Microwaves, like all home appliances, can behave erratically from time to time. If your microwave turns on or keeps running when you open the door – it's a problem. When the microwave turns on when the door opens, it's usually a sign of a faulty switch that needs replacing.

The latch on the door features a switch responsible for controlling the microwave functions, such as starting the timer or turning on the lights. If the switch is dysfunctional, the microwave keeps running when you open the door or turns on when you open the door.

Does that mean you need to toss out the appliance and buy a new one? Perhaps not.

Faulty Microwave Troubleshooting Tips

Why does my microwave turn on when I open the door? In most cases with microwaves continuing to run or starting to run when you open the door, it's the "interlock switch" causing the issue. This switch sends a signal from the door to the components in the machine responsible for starting and stopping the appliance.

When you encounter this problem, the first thing to do is ensure the microwave isn't running with the door closed when you press the stop/cancel button. If it's running in both instances, you likely have an issue with the control board, not only the switch.

Use a multimeter to customize your troubleshooting of the appliance if the issue is confined to it operating when you open the door. The multimeter allows you to test the electrical continuity of the appliance and confirm the problem lies with the interlock switch.

However, that step isn't always necessary, as it's almost guaranteed you're dealing with a faulty interlock switch.

Your Microwave Has a Faulty Door

A fault in the door is the most common problem causing a microwave to start running or keep running when you open the door. Some models may have two or three interlock switches in various locations around the door.

The interlock switch is the reason why the lights turn on in the microwave when opening the door. The interlock switch or switches connect to the door latch, ensuring the microwave only operates when the door is closed.

The steel prongs attached to the interlock switch detect if the door is open or closed. When they meet the contacts, it completes the circuit, signaling the motor to start operating. So, you'll need to check the door latch functions properly since a faulty latch usually complicates the problem with the interlock switch.

Microwaves with door defects can cause severe burn injuries for the user. The appliance can also damage nearby electronics. If your microwave turns on when the door opens, you must fix it, period.

The Microwave Switches Are Heat-Sensitive

Some microwave models feature heat-sensitive switches that sense the heat in your hands when opening the door. They can become dysfunctional, detecting heat from nearby appliances, and causing problems with the unit operating with an open door.

You'll need to isolate the microwave from other appliances near the unit to see if they're causing the problem. When checking the issue, use an inert and cool object like a pencil to operate the microwave buttons.

The Interlock Switches Remain Open

The interlock switch is the primary issue with a faulty microwave that runs when the door opens. They remain in the open position, causing the problem. Typically, the switches return to the original closed position after pressing them.

However, in a faulty microwave, the unit keeps functioning. That means that the microwave turns on as soon as you press the power button to activate the device. This is highly dangerous and can cause burn injuries.

Steps to Replace the Microwave Door Interlock Switch

Most microwave models have three switches located behind the control board. They are the primary, secondary, and monitor switches. These switches work with the door latch assembly to prevent the microwave from operating while the door is in the open position.

You'll need to fix the microwave to ensure safe operation when the door is only closed. You'll need some basic tools and parts like a screwdriver and control switch to help you with the task. Before you start the repair, unplug the microwave from the outlet and wait a minute or two for the charge to dissipate from the capacitor.

Compete the following steps to repair the unit after you're certain there's no risk of the microwave turning on while you work. The microwave turns on when the door opens no more after this!

1) Repair the Smartboard

Remove the upper panel of the cabinet and the keypad to access the smartboard. You'll find it located behind the keypad.

2) Locate the Interlock Switches

Find the interlock switches in the microwave door – there may be more than one. Refer to your owner's manual if you purchased your model new. If you bought it second-hand, search the manufacturer's website for the owner's manual, or contact the customer service department for an electronic copy.

3) Access the Electric Panel

Open the fasteners and take care not to damage them during the process. Next, open the electric panel and remove the switch assembly. Remove the switches from the board and take care not to damage it as you work.

4) Locate the Faulty Switch

When pressing the switches, they should go inside and come back into place. If the switches don't return to position, you can consider them faulty and needing replacement.

5) Replace the Faulty Switch

After identifying the faulty switch or switches:

1. Order the same switches online from the manufacturer or a service center near you.
2. Remove the faulty switches and replace them with the new ones.
3. Reassemble the parts and double-check your work.

Check if the fix solves the problem. Plug in the microwave, and if it doesn't turn on when the door opens, you've repaired the appliance.

Do I Need to Send the Microwave to a Service Center for Repairs?

If you don't have any experience working with appliances like microwaves, don't try to fix the problem yourself. You could end up doing more damage. Depending on the manufacturing brand, most microwaves come with a two or five-year warranty.

Trying to fix the microwave yourself could void your warranty if the appliance is still under warranty. If the microwave is still under warranty, let the manufacturer fix it for you, and you'll avoid the hassle of repairing it yourself.

Go online and type in the name of the manufacturing brand, along with "service center near me." Call the service center and tell them about your problem. They'll ask you if the appliance is still under warranty. Take it to the service center and get your repair ticket.

The manufacturer will fix the problem and issue you a new warranty to cover the repairs on the microwave.

FAQs for When the Microwave Turns on When the Door Opens

Great, the microwave starts when the door opens. We know how to fix it but what about the details? Let’s look at those extra questions that arise now.

Why Does the Circuit Breaker Trip When the Microwave Door Opens?

If you open the microwave door and the dedicated circuit breaker in the breaker box trips, you have an issue with the ceramic fuse or the door interlock switch in the appliance. The circuit detects a damaged or malfunctioning interlock switch as a fault and trips the breaker. You'll need to replace the interlock switches to resolve this problem. This can also happen with microwaves plugged into an extension cord if the cord isn't rated properly.

Is It Dangerous to Run the Microwave With the Door Open?

Yes, If the microwave keeps operating, and it's not just the fan and light, it presents a severe burn risk to the user. It's unsafe to be around it, and it can also damage other nearby appliances. Typically, this occurrence happens with older model microwaves, as newer models have safeguards in place to prevent this sort of thing. Remove the plug from the outlet immediately if you notice the microwave is still running when opening the door.

Can I Repair the Microwave Myself?

Yes. It's possible to repair the microwave yourself if you have the owner's manual, experience working with electrical products, a multimeter, needle nose pliers, and a screwdriver. However, most homeowners don't have any of those requirements. At best, you'll have a screwdriver and pliers. So, it's best to send it to the manufacturing brand's service center for repairs. Trying to repair it yourself will void the appliance's warranty.

Key Takeaways for When the Microwave Runs With the Door Open

• If the microwave continues to run after you open the door, it can present a health and safety risk to the user.
• You could sustain burns or eye damage, and the microwave could damage nearby appliances.
• In most cases, faulty interlock switches are the cause of the microwave running when the door is open.
• The interlock switches are easy to replace, and the parts don't cost much.
• However, the manufacturer usually recommends that the owner not attempt to repair the appliance themselves.
• If your microwave is still under warranty, take it to an authorized repair center. It won't cost you anything.
• If the machine is out of warranty, the service center should be able to repair it for a cost.
• Get a quote for repairs before authorizing the work. In some instances, the repairs might be close to or more than the price of a new microwave.

If Your Microwave Turns On When the Door Opens, Fear Not!

We’ve helped you narrow down exactly why your microwave turns on when the door opens, and it’s almost always the interlock switch. The most trouble you’ll have is in obtaining a new one, which means you’ll either order from the manufacturer or find a suitable 3rd-party alternative (which will be cheaper).  Swapping them out will be no problem for most with any experience, but if you have none, you can take the microwave to a professional repair shop.

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