What To Check When Your Microwave Turns On By Itself

Appliance Express
October 17, 2019
Microwave Repair

Microwaves are a staple kitchen tool, and generally, even cheap microwaves last a very long time without any problems that require extensive repair. However, one of the more odd and even unexpected problems that a microwave can manifest is just starting up by itself, empty and without provocation.No, it’s probably not because of ghosts. There are a few parts in a microwave that can malfunction in a way that may cause it to start up randomly. Unfortunately, while you might find it a little amusing at first, it can become a bigger issue. Not only are you wasting power, but a microwave running empty is not good on the appliance itself. It can cause damage to the microwave if it is producing heat. Running it empty for a short period of time is fine, but if it happens while you are away or for a longer period, you will most likely need a new microwave sooner rather than later as well as the fact that it can become a fire hazard.

Because it can be a waste of energy and is so hard on the appliance, you need to get this problem fixed up. Here are the most common suspects for this particular problem.

Stopping This Issue Before a Repair

You might not have the time to troubleshoot your microwave right this moment. If that is the case, you may want to unplug it when you are not using it. This means you do not risk damaging the microwave and it doesn’t become a fire hazard when you are out of the house. You can also try keeping the door ajar. However, both of these are temporary fixes to buy you time to find the actual cause.

It is also worth noting that in some cases, unplugging your microwave and leaving it unplugged for 15 seconds can work as a sort of reset. It is something that is worth a try but may not fix your issue. It is more for issues like stuck switches that get stuck on. Resetting can unstick it, but resetting won’t help something like a faulty control board, for example.

Keypad Membrane

If a keypad membrane is old or malfunctioning, it can actually activate the controls by itself. It is also worth knowing that many membranes are heat activated. This means that if your microwave sits above your stove or even by a heat vent, the ambient heat from those things can activate it.

If it is a heat issue, then it is more of a repositioning job rather than a replacement. If your microwave has been above your stove forever and it is just manifesting this issue, then the heat resistance on the touchpad has worn down and you will need to replace it. If it is a new microwave you have placed over your stove, you may want to consider replacing it with a model that does have a heat sensor that was developed specifically for over stove use.

While some models allow you to remove the control panel from the front of your microwave and replace the actual membrane behind it, many more actually require you to just replace the entire touchpad by not giving you access to the membrane. You will want to disassemble this part before ordering a replacement to find out which you need in order to make the correct replacement.

Control Board

The control board in your microwave is very much the brain of the appliance. It is from this board where all the signals are received and relayed. As such, when the control board starts to go faulty, it can manifest so many different symptoms, and yes, one of them is the appliance turning on by itself. When this happens, the control board is still sending signals that voltage should be supplied to the cooking components. So that is an issue.

Like the keypad membrane above, when replacing the control board, many microwaves require you to just buy a completely new control panel. If you can reach the control board, this means you can replace it. However, if you remove the control panel and find that it is a sealed and self-contained unit, then your replacement part will be the control panel unit rather than just the control board itself.

If you do just merely need to replace the control board, it is actually quite simple as it is just a case of unplugging the wire harnesses from the old one and plugging them into the new model while making sure it is properly lined up and mounted.

Stuck Switches

Are your issues less of “the heat is turning on” and more of “the light and turntables spin” when it comes to a microwave turning on by itself? This isn’t as serious of a problem. Those two parts use energy, but not as much as the heat-producing parts. Furthermore, they will cause wear to those specific parts, but not the more expensive parts of the microwave like the magnetron.

Yet, it is something that needs fixing, and the problem is that either the door interlock switch is stuck or the interlock relay on the control panel is stuck.

Again, you may need to replace the entire control panel to replace a stuck switch. You should also investigate the door interlock switch to make sure that it is clean. If it does seem pretty clean, replacing this switch requires you to disassemble your door.

Need Help?

When it comes to microwave repair, not everyone is so comfortable doing it themselves. This perfectly fine. Microwaves can hold a lethal charge in their capacitors even when unplugged. While the above repairs don’t require you to go anywhere near the capacitors, if you have to remove the case to remove the control panel, they will be exposed. If you want to make sure this repair and replacement is done safely and correctly the first time, contact us today. The professionals at Appliance Express are experts at getting all your appliances fixed up fast so you can get back to using them right away.


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