Question 1

the interior light bulb burned out, how do i change it on this over-the-range model?

Accepted Answer

DIAGNOSIS The bulb is a standard appliance bulb, but accessing it isn't as simple as just unscrewing a cover from inside the cavity. The bulb is housed in its own assembly near the top of the cooking area. FIX 1. Unplug the microwave. Safety first. 2. Open the door. You'll see one or two screws on the top front edge of the interior, near the light cover. 3. Remove those screws. The light cover (a plastic lens) should slide or hinge down. 4. The bulb is right there. It's likely a 40-watt T7 halogen bulb (sometimes incandescent). Let it cool if it was recently used, then unscrew it counter-clockwise. 5. Replace it with an identical type and wattage bulb. Don't use a higher wattage, as it can damage the socket or wiring. IF THAT DIDN'T WORK If you replace the bulb and it still doesn't light, the issue could be the light socket itself (corroded or loose wires) or the control board not sending power. That's less common than a simple burned-out bulb. HEADS UP Do not, under any circumstances, try to change this bulb while the unit is plugged in. You're working right near live electrical connections. Taking the minute to unplug it is the most important step.

Question 2

the vent fan seems weak, it doesn't pull any smoke from the stove

Accepted Answer

DIAGNOSIS This is almost always one of two things: the grease filter is completely clogged (see the other question), or the damper on the outside of your house (where the duct vents out) is stuck closed. FIX 1. First, clean that grease filter. A dirty filter blocks 90% of the airflow. 2. Set the fan to the highest speed. 3. Go outside and find where the vent duct terminates on your exterior wall. There should be a flapper (the damper) that opens when the fan is on. 4. Have someone turn the fan on high while you watch. The flapper should open freely. If it's stuck shut by paint, dirt, or a bird's nest, that's your problem. Clear the obstruction so it can swing open. IF THAT DIDN'T WORK If the filter is clean and the exterior damper opens, the fan blower wheel inside the microwave might be gummed up with grease itself. That requires a more involved disassembly to clean the squirrel cage fan. HEADS UP Make sure you're using the correct vent mode. This microwave can be set to vent outside or recirculate through charcoal filters. If it's set to 'recirculate' but you have a duct hooked up, performance will be terrible. Check the installation settings.

Question 3

the clock and settings keep resetting every time i turn off the kitchen breaker

Accepted Answer

DIAGNOSIS That's normal behavior, not a fault. This model doesn't have a backup battery to retain memory. When it loses all power (from a breaker trip or unplugging), it reverts to a default state, just like when it was first installed. FIX There's no fix, only resetting. After power comes back, you just need to reprogram the clock and any settings you use, like the child lock or favorite cook times. Press the 'Clock' button, enter the time with the number pad, and press 'Clock' again to set it. IF THAT DIDN'T WORK If the clock is resetting even when the microwave hasn't lost power—like it randomly goes blank while the kitchen lights are still on—then you have a loose wire connection or a failing main control board. That's a different and more serious problem. HEADS UP If you're going to be working on the microwave for any reason (like changing a light bulb or cleaning behind it), expect to reset the clock afterwards. It's just part of the process with this unit.

Question 4

the turntable motor stopped spinning, my plate just sits there

Accepted Answer

DIAGNOSIS The little motor that drives the turntable has either failed, or the coupling between the motor and the roller ring under the glass plate has come disconnected. Sometimes it's just a piece of food debris jamming the mechanism. FIX 1. Take out the glass plate and the plastic roller ring underneath. 2. Look down into the cavity floor. You'll see a small, white plastic drive hub in the center. 3. Manually rotate that hub with your fingers. If it spins freely with no resistance, the motor is likely dead. 4. If it's stiff or won't turn, there might be a piece of burnt food or a stray popcorn kernel jammed in there. Clear it out. IF THAT DIDN'T WORK If the hub turns but the motor doesn't spin when you run the microwave, the turntable motor itself has failed. It's a relatively small part that mounts underneath the cavity floor. Replacing it requires removing the microwave from the wall and disassembling the bottom. HEADS UP You can technically use the microwave without the turntable spinning, but your food will heat very unevenly—hot spots in the center, cold edges. It's best to get it fixed.

Question 5

how do you clean the grease filter on this thing? it looks like it doesn't come out

Accepted Answer

DIAGNOSIS It definitely comes out for cleaning—it's designed to. People often miss the simple release mechanism because it's not super obvious. A clogged filter reduces venting performance dramatically. FIX 1. Open the microwave door. Look at the very bottom of the front panel, right under the control area. 2. You'll see a small, recessed latch. Push it firmly to the right (or sometimes down, depending on model). 3. The entire filter assembly—the metal grille—will now tilt forward from the bottom. 4. Pull it straight down and out. You can wash it in the sink with hot, soapy water or even in the dishwasher (top rack). Let it dry completely before sliding it back in. IF THAT DIDN'T WORK If the latch feels stuck, don't force it. Kitchen grease can act like glue. Try pressing the latch while gently wiggling the filter grille from the bottom to break the grease seal. HEADS UP Clean this filter at least once a month if you cook with any regularity. A filter caked with grease is a fire hazard and makes your vent fan useless, letting all that smoke and smell back into your kitchen.

Question 6

it makes a loud humming or buzzing noise when it runs, way louder than it used to

Accepted Answer

DIAGNOSIS That's usually the cooling fan for the magnetron (the part that makes the microwaves). Over time, the bearings in that fan motor can wear out or get gummed up with kitchen grease, causing a grinding or loud hum. It could also be the fan blade hitting something. FIX 1. Unplug it. 2. Remove the grease filter and wash it—a clogged filter makes the fan work harder. 3. If the noise continues, the fan is inside the top compartment. You'll need to remove the outer cover. Once inside, check for any debris touching the fan blades. 4. Spin the fan blade by hand. If it feels gritty, binds, or wobbles, the fan motor assembly needs to be replaced. IF THAT DIDN'T WORK A less common cause is a failing magnetron itself. If the fan is spinning freely and clean, but the loud buzz is coming directly from the large, heavy component on one side (the magnetron), it's likely the source. Magnetrons do eventually wear out. HEADS UP That fan is critical for preventing the magnetron from overheating. Don't ignore this noise and keep using the microwave, or you could cause a complete and more expensive failure.

Question 7

the light and fan come on but it won’t heat up when i press start, no error code

Accepted Answer

DIAGNOSIS The microwave is getting power to its 'housekeeping' circuits (light, fan) but the high-voltage system that actually creates the microwaves isn't engaging. The most common culprit is a failed door switch. FIX 1. Unplug the unit. 2. The door switches are activated by little plastic tabs on the door. Open the door and look for them. 3. Carefully inspect the plastic actuator tabs on the door itself. If one is broken or worn down, it won't press the switch. 4. If the tabs look fine, the switch itself is likely bad. You'll need to remove the outer wrapper to access and test the switches with a multimeter. IF THAT DIDN'T WORK If all door switches check out, the next suspect is the high-voltage relay on the main control board. It's a small component that sends the 'go' signal to the magnetron. When it fails, everything seems normal except the heating. HEADS UP Never, ever try to run the microwave with the outer casing removed or the door interlock system bypassed. The radiation exposure is extremely dangerous. If the fix involves the internal switches or high-voltage components, consider professional help.

Question 8

my lg microwave just shows F-3 on the display and won’t do anything, what does that mean?

Accepted Answer

DIAGNOSIS That's the oven temperature sensor error. The little sensor that checks how hot the oven cavity is has either failed or the wire to it has come loose. The microwave locks up because it can't tell if it's safe to run. FIX You'll need to get behind the control panel. Unplug the microwave first—safety is key here. Remove the grille at the top front (it usually snaps off). You'll see screws holding the outer cover over the electronics. Take those off, and you'll see the sensor, a small nub with a wire, clipped into a hole in the oven cavity. Check that the wire connection is snug on the sensor. If it is, the sensor itself is likely bad and needs replacing. IF THAT DIDN'T WORK If the sensor connection was fine, the problem might be on the main control board. A bad connection there can cause the same error. You'd need to check the wiring harness that plugs from the sensor circuit into the main board for any damage. HEADS UP This is not a filter or cleaning issue. The F-3 code is a hard fault. If you're not comfortable working with live electronics, it's time to call a technician. Forcing it to run could be a fire risk.

LG LMV1831SS Over-the-Range Microwave

Other Microwaves