It is not an unusual problem. You want to cook something in the microwave but it doesn’t seem to work. It appears to have power but nothing but the light comes on. Do you need to get a new microwave? Depending on how old it is, probably not.
An LG microwave not working but having power can be the symptom of any number of problems. However, the most common issue is going to be the thermal fuse. It can also be a diode or the magnetron but those usually have other symptoms too.
Read further to figure out how to diagnose your microwave’s problem and possibly fix it yourself.
Take the Easy Solutions First
It’s always a good idea to work on the simplest way to fix an appliance first. In the case of a non-working microwave, check to see if the cord is properly plugged in. While you are looking behind the microwave, look at where the cord goes into the oven and make sure it’s in good order.
A damaged or burned receptacle could cause the oven not to work, considering all the safety features it has inside it.
You might want to go ahead and reset the GFCI fuse on your power outlet.
Since your microwave appears to have power, it isn’t going to be a tripped circuit breaker or even the GFCI switch. However, resetting the GFCI fuse could give full power back to your oven if that was a problem.
Symptoms of a Blown Fuse
Other signs than the obvious lack of function will show you that your problem is likely a blown thermal fuse. It is one of the few things that will result in the microwave still having power but failing to work.
A blown diode would mean the microwave works but wouldn’t heat. A failed magnetron has the result of no power and an accompanying clicking sound. A burning smell is generally the result of the control board of wiring being damaged.
Test the power buttons to see if any work. This is another sign that it’s the thermal fuse. However, there is one more thing you should check before you get on the phone with customer support.
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The Child Lock
LG microwaves come with a safety feature to keep children from using the microwave unsupervised. It has a child lock. Sometimes, the child lock can accidentally be activated and that causes the power to be on but nothing to work. The buttons won’t work, the timer won’t work and the oven will not cook.
You will need to see if this is the problem. Press the enter or start button for at least four seconds. It will either show an “L” appearing or it will disappear. An “L” showing up on the display means the child lock wasn’t on. A disappearing lock icon means it was on and now you’ve deactivated it.
You will need to deactivate it if it appears. Just release the button and press it again for four seconds. The icon will disappear.
What Does the Thermal Fuse Do?
The purpose of the thermal fuse is to shut down the microwave if it starts running too hot. It could be the oven stops during cooking. If that is related to a tripped breaker and is the thermal fuse, the microwave will restart when it cools.
However, a blown thermal fuse means the microwave won’t restart.
While this would be an easy project for most DIY people, most home experts advise against trying to test the thermal fuse yourself. The reason is because up to 5,000 volts of electricity is stored in a microwave and that energy remains charged even after the appliance is unplugged.
Such a shock would injure, or even kill, a person. Most experts say it’s best to let licensed professionals handle matters that involve the internal workings of a microwave.
A thermal fuse can’t be repaired. They are unfixable after they burn out. They are one of those parts that will need to be replaced to get your microwave to work well again.
There are other fuses in a standard microwave. Slamming the door shut sometimes will cause the microwave to not work. However, usually, it would also cause it to go dark without power too.
Door Latch Assembly
The door latch is another ongoing problem that could cause the microwave to fail to work. Typically, a broken door latch will not allow the light to come on either.
Door latches are plastic pieces that can break over the years. Their purpose is to move when you open or close the door. This signals to the control board that the door is firmly closed and cooking can begin.Damaged springs will prevent the door from properly closing and that will stop the microwave from operating correctly.
This is a part that you can replace fairly easily. You will unplug the microwave, and remove the side door panel to look at the latch.
- Disconnect the old latch and connect the new one. It shouldn’t take more than a few minutes.
- Reassemble the panel front, reconnect the microwave to power, and test the door.
- Do a cooking test to see if that works.
The only other possibility of a problem causing your microwave to not work is faulty door switches.
Most microwaves have three door switches and each relays messages to the control board once the door is closed. Your microwave will have power but won’t work if one blows. It is usually the bottom switch that seems to fail to cause this problem.
The problem with door switches is that even failed ones would still allow you to use the program and keypad. The microwave just wouldn’t cook. The fact that you can’t use anything on your microwave points to the thermal fuse.
The thermal fuse shuts everything down when it goes.
How much does a thermal switch cost to repair?
It costs between $50 to $100 to replace a thermal fuse. That includes parts and labor. The fuse itself is cheap and this is considered to be one of the easiest microwave repair jobs a tech can do. It shouldn’t take more than an hour to fix.
Will there be any signs the thermal fuse is going bad?
The only strong signal you have a thermal fuse going bad is it may stop your microwave from operating repeatedly until it fails. Your microwave is cooking but stops. Later, it starts cooking again.
That is what the thermal fuse is designed to do. It stops your microwave from functioning until it cools down. However, you will know it’s operating properly when it cuts all power from your oven. Your oven works great once it cools down and doesn’t give you a lot of problems later
A thermal fuse going bad will do this a lot more often and it may not cut the power to the microwave. Even so, your oven works later. This ongoing issue will result in your oven eventually quitting working altogether.
When To Replace a Microwave?
Signs regarding how your microwave works will indicate you need a new one. Certainly, a microwave that sparks, smokes, or produces a burning smell needs to be replaced immediately.
Other signs include loud, horrible sounds it produces while it’s running, problems with the door shutting or not sealing, and the keypad getting harder to press where functions work. A big signal is if food just doesn’t cook well like it used to.