- PREHEAT - the indoor fan pauses while the indoor piping warms, so the unit does not blow cold air at you. This is the single most common "my LG is not heating" report, and it is the unit being considerate.
- DEFROST - the system briefly runs in cooling to melt frost off the outdoor unit, and the indoor fan pauses while it does.
- WATER DROP - used on some displays for preheating or defrosting. The fan may pause and the louvers may close to prevent a cold draft.
If any of those is showing, wait a few minutes. Nothing is broken.
Two more displays that are not faults
Lo and Hi are temperature messages, not failure codes - the unit reporting that the room is very cold or very hot. On a cold morning, Lo is exactly what you would expect to see on a system that is about to start heating.
CLEAN FILTER is a maintenance reminder counted from operating hours, not a sensor reading your actual filter. It can appear on a perfectly clean filter - and, more usefully, a genuinely filthy filter will not necessarily trigger it. Clean on a schedule, not on the prompt.
Safe checks
- Wait out PREHEAT, DEFROST or WATER DROP before concluding anything.
- Mode and setpoint. HEAT, not AUTO or FAN, several degrees above room temperature.
- Filters - regardless of whether CLEAN FILTER is showing.
- Outdoor unit clearance. It pulls heat from outside air, so snow against the coil, ice from a roof drip line or leaf pack will starve it. Clear it with the power off.
- Know your model's floor. Below its rated minimum outdoor temperature, reduced output is the published spec rather than a fault - check your model in the database.
- Power cycle at the breaker for five minutes.
When to stop and call a technician
If the display shows a CH code - LG's actual fault codes are numbered, like CH 04, CH 05 or CH 21 - you are past the homeowner list. Those cover sensor, communication, fan-motor and compressor faults, and they are diagnosed with instruments. Look yours up in the LG error-code library before calling, so you can tell the technician what the unit is reporting.
Call as well if the unit cools normally but never heats, which points at the reversing valve, or if the outdoor coil ices over and never clears through a defrost cycle.
One thing worth knowing about LG specifically
LG mini splits are professional-install equipment and are not sold through our affiliate partners, so there is no buy button on this site for them and no incentive for us to push you toward a replacement. If a quote starts pointing at a compressor or an inverter board on an older system, our installation cost estimator will size the replacement side honestly, and the product finder will show what your current model's published capacity and cold-weather rating actually are.