Your Microwave Comes On When the Door Is Opened — Here’s Why

1. The Door Switch Is Jammed

Microwaves include a safety feature called a door switch, which activates when the door is opened to prevent the appliance from running. If your microwave turns on with the door open, a malfunctioning door switch is likely the culprit. It might be blocked by food particles or debris.
To address this, close the door, unplug the microwave, and inspect the area around the door for any buildup. Clean away any debris, but if something is stuck in the switch itself, it may be time to call a professional repair technician for a thorough inspection and cleaning.

2. A Faulty Switch Is Shorting the Magnetron

The magnetron is the component that generates the microwaves used to heat food. However, a malfunctioning door switch can cause a short circuit to the magnetron’s power supply. When this occurs, you might observe the microwave’s fan running as soon as the door is opened. Additionally, a faulty magnetron can produce a loud buzzing noise.
If your microwave turns on with the door open, it’s best to unplug it and cut the power at the circuit breaker until a professional technician can take a look. They may need to replace the door switch or the magnetron.
Microwave repairs should always be handled by experts. These appliances contain a high-voltage capacitor that can hold a charge even when unplugged, presenting a serious risk of shock or electrocution. For safety, avoid attempting any DIY repairs.

3. The Light Is On for Convenience

When you open your microwave door and the light turns on, that’s a clear indication that the appliance is operating normally. The interior light is useful, providing better visibility when you’re taking out hot dishes. As long as just the light activates—without the fan kicking in—your microwave is in good working order.

4. The Fan May Be Broken

Normally, a microwave’s fan shouldn’t run when the door is open. If it does, there might be an issue with the fan itself. To check if the fan is the only problem, try this: Put a microwave-safe container filled with water inside the microwave, leaving the door slightly ajar. Step back during the test. After about a minute, see if the water has warmed up.
If the water is warmer, it means the microwave is generating microwaves with the door open, indicating a bigger issue than just the fan. However, if the water remains the same temperature, the fan might be malfunctioning and could need professional replacement.

5. The Control Board May Be Faulty

If your microwave keeps running even when the door is open, there might be a problem with its control board. Another red flag for control board or wiring issues is if the appliance repeatedly trips the circuit breaker.
Since this involves electrical components, it’s a good idea to call a professional SD Appliance Repair technician, to take a look. If a critical part is damaged, it might make more sense to replace the entire microwave instead of investing in costly repairs.

What to Do If Your Microwave Runs With the Door Open

Microwaves contain components that can pose serious safety hazards, from the powerful microwaves produced by the magnetron to the high voltage stored in the capacitor. Ignoring these issues or attempting a quick fix can be dangerous.
If your microwave turns on when the door is open, it’s important to get a professional SD Appliance Repair technician to examine it. They can assess whether repairing the appliance is a safe and worthwhile option.