LG Microwave: Won't Start or Turn On
Commonly a door-switch fault, a blown fuse, or a control-board issue. Add a photo of your LG Microwave in the box below: the Triage Profile says what it is, how urgent it is, and who to call.
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In the next five minutes
Safe first steps, before the call. Nothing here needs a tool.
Stop the microwave and switch off its breaker, or unplug it if the plug is dry and easy to reach.
Take a photo of the microwave and any code on the display, without opening anything.
Don’t use it again until it’s checked, and keep people away from it.
Everything else about this problem
Is it an emergency?
Is an LG microwave that won't start an emergency?
Usually not, but it can be. Because this can be an emergency, leave it off and get it checked; don't reset it or turn it back on. Stop and call a pro if it keeps tripping the breaker or smells like burning.
Symptoms & causes
If your LG microwave is completely dead, showing no display or power, the primary issue could be a tripped circuit breaker or a blown thermal fuse. Alternatively, if the unit hums but doesn't heat, or the display is on but nothing happens when you press start, a faulty door switch or a problem with the high-voltage components like the magnetron might be the cause. These symptoms often point to a safety mechanism preventing operation or a component failure in the power supply circuit.
Tools & parts
You will need a multimeter to test for continuity in components like the thermal fuse, door switches, and capacitor. A basic screwdriver set (Phillips and flathead) is essential for disassembling the microwave's casing and accessing internal parts. Insulated needle-nose pliers are useful for handling wires and safely discharging the high-voltage capacitor.
Safety first
Always unplug your LG microwave from the wall outlet before attempting any inspection or repair to prevent severe electric shock. Be aware that the high-voltage capacitor inside a microwave can store a lethal electrical charge even after the unit is unplugged, so it must be safely discharged using an insulated tool before touching any internal components. Wear insulated gloves and safety glasses to protect against electrical hazards and potential arcing during the repair process.
When to call a pro
If the magnetron is suspected to be faulty, indicated by a humming sound but no heating, or if the unit sparks, professional service is highly recommended due to the extreme high voltage involved. Issues with the main control board, especially if tests go beyond basic continuity checks, often require a technician's expertise for proper testing and replacement. Any repair involving the high-voltage transformer or capacitor, particularly if you are unfamiliar with safe discharge procedures, should always be handled by a certified appliance repair technician.
Questions people ask
Why won't my LG microwave turn on after a power surge?
A power surge can trip your home's circuit breaker or blow the microwave's internal thermal fuse, which is a safety device designed to protect the unit from overheating. First, check your home's electrical panel for a tripped breaker, then inspect the microwave's thermal fuse for continuity with a multimeter.
Can a faulty door switch prevent my LG microwave from starting?
Yes, LG microwaves incorporate multiple door interlock switches that must all be correctly engaged for the unit to operate, and if even one is faulty or misaligned, the microwave will not start as a safety measure. You can test these switches for continuity using a multimeter to identify a defective one.
What if the display is on but the microwave won't heat?
If your LG microwave's display is active but it fails to heat food, the problem likely lies with the high-voltage components such as the magnetron, high-voltage capacitor, or diode. These parts are extremely dangerous to test and replace due to the lethal stored energy, so professional service is strongly recommended for this specific issue.
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What it is, how urgent, who to call
Add a photo of your LG Microwave in the box at the top. The Triage Profile says what it is, how urgent it is, and who to call.