An LG air conditioner that leaks water has a drainage problem, an airflow problem causing ice to form and melt, or an installation problem that prevents water from flowing where it is supposed to go. The water you see on the floor, on the wall below the indoor unit, or dripping from the window unit is condensate — the same water that forms on a cold glass on a humid day — that the air conditioner is supposed to collect and drain away. It is leaking because the drain path is blocked, the unit is tilted the wrong way, the filter is so dirty that ice is forming and melting in uncontrolled bursts, or the condensate pump has failed.
The location of the water tells you where the problem is. Water dripping from the front of a wall-mounted LG mini-split indoor unit means the drain pan is overflowing because the drain line is clogged or the unit is not level. Water pooling under a window AC inside the house means the unit is tilted inward instead of outward. Water dripping from an outdoor condenser unit in cooling mode is normal — it is condensate from the suction line, not a leak. Water that appears only occasionally and coincides with the unit shutting off is a frozen coil thawing, not a drain problem.
1. Clogged Condensate Drain Line: The Most Common Cause
Every LG air conditioner produces condensate during normal cooling operation. That water drips into a drain pan beneath the evaporator coil and flows out through a drain line. When the drain line clogs with algae, mold, dirt, or insect nests, the water backs up in the pan until it overflows — onto the floor, down the wall, or out the front of the indoor unit. An LG mini-split that drips water from the lower edge of the indoor unit, especially on the right or left side where the drain connection is located, has a clogged drain.
To clear the drain on an LG mini-split, locate the drain outlet: a small PVC or vinyl tube exiting the indoor unit near the wall penetration on the right or left side. Remove any cap on the end of the tube. Use a wet-dry vacuum to suction the line from the outside end for 1 to 2 minutes. Pour a cup of warm water mixed with a few drops of bleach into the drain pan behind the front cover to kill algae inside the pan and the drain line. On an LG portable AC, the internal water tank may be full. Most LG portables have a drain plug on the back or bottom of the unit. Unplug the unit, place a shallow pan under the drain plug, remove the plug, and drain the tank completely.
LG mini-split drain location: On most LG wall-mounted units, the drain hose exits the indoor unit on the right side when facing the unit, and runs through the wall bundle alongside the refrigerant lines to the outside. If the drain line sags or has a low spot between the indoor unit and the wall exit, water pools in the sag and algae grows. The drain line must slope continuously downward from the indoor unit to the exit point. No exceptions.
2. Dirty Air Filter: Ice Forms, Then Melts in Uncontrolled Floods
A clogged air filter restricts airflow across the evaporator coil. The coil temperature drops below freezing, and ice forms on the coil fins. When the ice layer grows thick enough to completely block airflow, or when the unit cycles off and the ice begins to melt, a large volume of water floods the drain pan faster than the drain line can carry it away. The pan overflows, and water drips from the front of the unit or down the wall.
An LG unit that leaks water intermittently — not constantly, but in occasional bursts, often shortly after the unit cycles off — is experiencing a frozen coil thaw cycle. Clean the air filter. On an LG mini-split, lift the front panel, pull the filter tabs, and rinse the filters under warm water. On an LG window unit, slide the filter out from the front grille. On an LG portable, the filter is behind the rear panel. Clean filters every 2 to 4 weeks during the cooling season. After cleaning, run the unit in FAN ONLY mode for 30 to 60 minutes if the coil is frozen, to thaw the ice without producing more.
3. Unit Not Level: Water Flows the Wrong Way
An LG window AC must tilt slightly toward the outside — roughly ¼ inch of downward slope per foot of unit depth. The tilt ensures that condensate flows to the outside of the window and drips onto the ground, not into the room. If the unit is level or tilted inward, water pools in the condensate pan inside the room, eventually overflowing onto the floor or through the front grille. Window frames settle over time. A unit that was correctly tilted when it was installed five years ago may no longer be tilted correctly.
Check the tilt with a bubble level on top of the unit. The bubble should be slightly toward the outside. Adjust the mounting brackets or add shims under the front edge of the unit to restore the correct outdoor tilt. An LG wall-mounted mini-split must also be level side-to-side. If the indoor unit tilts toward the side opposite the drain connection, condensate pools at the wrong end of the drain pan and overflows rather than reaching the drain outlet. Check the indoor unit with a level. If it is not level, the mounting plate has shifted and must be re-secured.
4. Condensate Pump Failure: Water Has Nowhere to Go
LG ducted air handlers, ceiling cassette units, and some mini-split installations in basements or interior rooms use a condensate pump to lift the water to a drain point above the unit. When the pump fails (the motor burns out, the float switch sticks, or the discharge tube clogs), the water has no way to leave the drain pan.
The pan fills, the float switch (if working) cuts power to the unit, and water may leak from the unit housing.
If the LG unit uses a condensate pump, it is typically a small plastic box mounted near or inside the indoor unit with a vinyl discharge tube running to a drain. Verify the pump is receiving power.
Pour a cup of water into the pump reservoir to test the float switch. The pump should activate and pump the water out within seconds. If the pump hums but does not pump, the impeller is jammed or the discharge tube is clogged. Clean the tube with compressed air or replace it.
A replacement condensate pump costs $60 to $150 and takes a technician 1 to 2 hours to install.
5. Low Refrigerant: Frozen Coil, Then Water Everywhere
An LG AC with low refrigerant runs the evaporator coil at a temperature below freezing. Ice forms on the coil. When the ice melts — either when the unit cycles off or when the homeowner notices the problem and turns the unit off — the meltwater overwhelms the drain pan. The water leak is not the primary problem. The low refrigerant is the primary problem. The water is a symptom of the frozen coil that the low refrigerant caused.
Signs that the water leak is refrigerant-related rather than drain-related: the unit was cooling poorly before the leak appeared, ice is visible on the evaporator coil or the suction line at the outdoor unit, and the leak occurs in a large burst when the unit cycles off rather than as a continuous slow drip.
A refrigerant leak in an LG window or portable AC is almost never worth repairing (the sealed system repair costs more than a replacement unit). An LG mini-split or central system with a refrigerant leak should be diagnosed by an EPA-certified technician. Leak repair and recharge costs $400 to $1,500.
6. LG Window and Portable AC Specific Leak Causes
Window unit rear drain hole clogged. Many LG window ACs have a drain hole on the bottom of the rear section that allows condensate to drip directly outside. If this hole is clogged with dirt, leaves, or insect debris, water backs up into the unit and leaks inside. Locate the drain hole on the bottom of the unit outside the window and clear it with a pipe cleaner or a small screwdriver.
Portable AC internal tank full. LG portable ACs collect condensate in an internal tank. Most models have an auto-evaporation feature that uses the condenser fan to evaporate the condensate and exhaust it through the vent hose, reducing the need for manual draining. In very humid conditions, the auto-evaporation cannot keep up, and the tank fills. The unit displays a FULL TANK indicator or error code and shuts off. Drain the tank manually through the drain plug on the back or bottom of the unit.
Window unit installation gaps. Warm, humid outdoor air leaking into the room around the sides of the window unit causes excessive condensation on the cold surfaces inside the unit. The condensate production exceeds the drain capacity, and water leaks from the front. Seal the gaps between the window unit and the window frame with the accordion side curtains and weatherstripping foam. No outdoor air should enter the room around the unit.
FAQ: Common Questions About LG AC Water Leaks
Is it normal for the outdoor LG condenser unit to leak water?
Yes. In cooling mode, the outdoor unit’s suction line and compressor are cold, and water vapor in the outdoor air condenses on these cold surfaces, drips onto the base pan, and drains out through weep holes in the bottom of the unit. This is normal operation, not a leak. The outdoor unit should produce condensate on a humid day. If the outdoor unit is producing excessive water — a continuous stream rather than a drip — the indoor coil may be freezing and the system may be low on refrigerant. But a moderate drip from the outdoor unit in humid weather is exactly what a properly functioning air conditioner does.
Why is my LG mini-split leaking water in the winter?
In heating mode, an LG mini-split reverses the refrigeration cycle. The outdoor unit becomes the evaporator and collects frost that must be periodically melted through a defrost cycle. The indoor unit should not produce condensate in heating mode. If the indoor unit is leaking water during heating, the drain line is clogged with debris from the cooling season, and rainwater or snowmelt is entering the outdoor portion of the drain line and backing up into the unit. The clog must be cleared from the outside end of the drain line.
Find Where the Water Is Coming From, Then Fix the Path
An LG AC leaking water has a drain that cannot carry water away, a coil that is producing more water than the drain can handle, or a unit that is tilted in the wrong direction. The drain clog is the most common cause — clear it with a wet-dry vacuum and a bleach flush. The dirty filter is the second most common — the ice it creates melts in floods that overwhelm the drain pan. The incorrect tilt is the third — fix it with a level and a shim.
If the filter is clean, the drain is clear, the unit is level, the pump is working, and water is still leaking, the coil is freezing from low refrigerant, and the melting ice is the water source. At that point, the water is a symptom of a refrigeration problem. Fix the refrigeration problem — find and repair the refrigerant leak — and the water stops.
