Why Is My LG Microwave Not Cycling Properly?

Microwaves are supposed to be simple, so it’s always annoying when they don’t function correctly. If you’ve noticed that your LG microwave isn’t cycling properly, you might be thinking it’s time to purchase a new one. Before you do, try the tips in this guide. Our troubleshooting and repair advice is simple enough for a novice DIYer. With just a bit of effort, your LG microwave will be up and running again in no time!

This guide applies to most popular LG microwave models, including: 

863.5939

ACO1860AS

EM1204S

EM120S

EM3321S

LCRT2010ST

LMH2016ST

LMHM2017ST

LMV1630ST

LMV1680BB

LMV1680ST

LMV1680WW

LMV1683ST

LMV1813ST

LMV2031ST

LMVM2055ST

MA1005W

MA1272MW

MBBS/01

MMV4205AAW

MMV5156AAS

Microwave DIY Safety

Before you begin, it’s important to understand the potential dangers involved in microwave repair. While safety is important in all DIY projects, microwaves have potential and unexpected dangers that other appliances do not.

Potential for electrocution

Microwaves contain a part called a capacitor, which stores electricity. Unlike most appliances, the capacitor retains a charge even when the microwave is completely disconnected from its power source. Touching the capacitor can cause an electric shock that can lead to severe injury or even death. 

Potential for radiation leaks

Microwaves are engineered to prevent microwave radiation from escaping the interior. If DIY repairs damage the shield, radiation leakage can occur. This is a risk to health and safety. 

Due to these unique risks, we recommend only attempting electrical repairs on a microwave in a limited capacity, such as repairs to the door or turntable that do not involve working with the internal parts. It’s also important to not attempt any repairs you aren’t comfortable with and to contact a technician if you feel out of your depth. 

Check the Power Supply

If your LG microwave isn’t cycling, the first place to check is the power supply. If the power supply is faulty, your microwave won’t be able to cycle or function in any way. If this is your problem, your microwave won’t be cycling. It also won’t have a functioning display or interior light. Here’s what to check:

• First, check the plug. Make sure it’s securely plugged into the outlet and the outlet is turned on (if it has a switch).
• Next, check the circuit breaker. The circuit breaker panel is usually located in your basement or garage, or in the hallway if you live in an apartment. Check that all of the breakers are in the ‘on’ position. Reset any that have tripped. 
• Check if the outlet is functioning by plugging a different appliance in. 
• Check if the power cord is damaged or frayed.
• Make sure the microwave is plugged into the outlet directly and that you aren’t using a power strip or extension cord as this can cause power supply issues. 
• Once you’ve fixed any power supply issues, run a test cycle to see if the microwave is now cycling properly. If the issue persists, move on to the next step in this guide. 

Check the Turntable Mechanism

The microwave turntable mechanism supports the glass plate and enables your food to turn to promote even cooking. If the mechanism is damaged, off-center, or obstructed, then it won’t be able to turn properly, which can make it seem like your microwave isn’t cycling. If this is your problem, your microwave might still light up and make a noise when you try to use it, but the glass plate won’t rotate. Here’s how to fix it:

• First, check that the glass plate is properly seated on the drive spindle and that the roller ring is correctly aligned. 
• Check the wheels on the roller ring. They can become blocked with food spills and grime, preventing them from properly rotating. 
• Try to manually rotate the drive spindle. If it appears blocked or obstructed, check if anything is preventing it from turning. 
• If you suspect a motor issue, you can test the motor with a multimeter for continuity. If it appears faulty, you can either replace it yourself or engage a professional technician to replace it for you. 

Inspect the Door Latch and Door Switches

The microwave door latch ensures that the door is properly closed and sealed, preventing microwave radiation from escaping while the microwave is operating. To ensure safety, LG microwaves are programmed to not run if the door is open. However, if the door latch is damaged or blocked, the microwave may sense that the door is open even when it’s closed. Here’s what to look for:

• Make sure the light turns off when you close the door. If it stays on, it’s a good indication there’s a latch issue. 
• Check the latch for damage or obstructions. If anything appears to be blocking the latch, such as a piece of plastic packaging or some food residue, make sure it’s completely removed and test to see if it’s working. 
• Check your door alignment. If the hinge is loose, the door latch won’t properly connect. Try to tighten the hinge and then check to see if the door is now closing properly. 
• If none of that works, there may be an issue with the latch continuity. Use a multimeter to test the door switches for continuity. If any show no continuity, they will need to be replaced. You can source a replacement part online and replace it yourself, or you can hire a professional microwave repair technician.

Other Possible Causes

If none of these fixes solve the issue, there may be a more serious problem. All of the below issues require opening the microwave cabinet to repair, which is not recommended for people without the necessary qualifications. These include:

• Blown fuse
• Malfunctioning magnetron
• Failed capacitor
• Faulty control board
• Burned out diode

If you suspect that your microwave isn’t cycling because of any of these issues, it’s best to call a professional microwave repair person to find and resolve the problem.