LG air conditioner errors or error codes: a useful guide

A code on the screen of an LG air conditioner is rarely a minor detail. It is usually the most direct way the unit has to warn that something does not fit: a sensor reading outside the expected range, a communication problem between boards, irregular voltage, or a blockage pushing the system to protect itself before going any further. In practice, these warnings save time and prevent more serious damage when they are interpreted calmly and without improvisation.

If you have a problem with your air conditioner, you can use our free error code finder. From there, you can find out what all the errors mean and fix them easily and effectively.

How to read what an LG unit is showing without losing track

LG does not use a single warning format across its entire range. Many wall-mounted split systems display sequences with CH, while other models show individual letters, flashing lights on the panel, or signals linked to the wired remote control. The language changes, but the logic is the same: the unit identifies an anomaly and translates it into a code that narrows down the source of the fault. That precision matters because the same symptom, such as a loss of cooling, can hide very different causes.

The difference between a temporary message and a persistent fault is also key. Power cuts, voltage spikes and certain electrical instabilities can trigger codes that disappear after a complete reset. LG recommends cutting the power for around five minutes, powering the unit back up and observing whether the warning appears again. If the code returns, it is no longer advisable to think of it as a simple temporary glitch.

In modern units, self-diagnosis works like a flashlight illuminating the weak point. It does not tell you everything, but it provides a great deal of guidance. A sensor, a fan, a communication line or the refrigeration circuit can leave a very specific trace on the display. Understanding that trace prevents randomly removing parts and helps distinguish a household issue from a technical one.

The most common codes and what they reveal

Among the warnings that appear most regularly are CH01, CH02, CH04, CH05, CH07, CH09, CH10, CH38, CH61, CH66 and CH93. Each one points to a different area of the system, but they all share a central idea: the air conditioner has detected something that compromises its normal operation and needs to slow down or limit its activity so the problem does not get worse.

CH01 is usually associated with the indoor temperature sensor, while CH02 points to the outdoor sensor or the pipe inlet sensor, depending on the model. CH04 is linked to the drain or condensate pump, an area that becomes especially sensitive when water builds up. CH05 and CH66 usually indicate poor communication between the indoor and outdoor units, a type of fault that can be caused by wiring as well as by a recent installation that was not properly finished.

Other messages are more mechanical. CH07 appears when the system detects incompatible modes in multi-zone or 2-in-1 installations; CH09 and CH10 point to the outdoor fan or the BLDC motor; CH38 and F4 usually warn of low refrigerant; CH61 warns of overheating; CH93 refers to a communication problem which, in more recent models, may also indicate that the outdoor unit is not receiving the correct power supply. The pattern is clear: the code number is not decorative, it is a diagnostic clue.

Sensor, drainage and ventilation: the three areas that come up most often

Sensors are small, but they control a large part of the unit’s behavior. They measure temperature, pressure and other variables that the electronic board uses to decide how hard to work, when to start and when to stop. If one of them sends an erratic reading, the air conditioner may cool poorly, shut off too early or force the compressor unnecessarily. That is why warnings such as CH01, CH02, CH41, CH44, CH45, CH46, CH47 or CH65 usually deserve serious attention.

Drainage also appears frequently on the fault map. In ceiling units or systems that produce a lot of condensation, CH04 indicates that the water is not draining as it should. In portable and window units, the situation changes: in certain models, the tray may fill up and show FL or CH04/FL, especially in high humidity or on rainy days. In these cases, condensation does not always mean a serious fault, but it is a sign that the unit is working at the limit of its natural drainage capacity.

Ventilation completes the triangle. A dust-loaded filter, a covered grille, an outdoor unit enclosed on a balcony with no way for air to escape, or a leaf stuck in the fan can trigger CH61, CH09 or CH10. The air conditioner, which needs to breathe in order to provide cooling, starts to struggle like a runner with a tight chest. The result is usually more strained noise, weak airflow or a protective shutdown.

Communication between units: when the system stops coordinating

CH05, CH53, CH66 and CH93 belong to an especially delicate family of errors. They are not about comfort, but about the connection: the indoor and outdoor units stop exchanging the information they need to start, modulate or maintain the cycle. In inverter systems, where the electronics operate continuously, weak communication can throw everything out of order within seconds.

This type of fault often appears after an installation, relocation or electrical work. A loose wire, a reversed connection, a poor ground or an unsuitable terminal block may be enough to leave the unit without coordination. In some models manufactured after 2021, the indoor and outdoor units may also require independent power supplies; if one of them is not receiving power, the symptom may look like a communication fault when the real problem is actually the power supply.

There is also an important practical nuance: when an error from this group appears immediately after installing or moving the appliance, the source is usually closer to the installation than to an internal breakdown. That does not make it trivial, but it does guide the search. Checking the wiring, confirming the connections and making sure both units are receiving power correctly matters more than repeatedly trying to restart the system.

The role of electricity: voltage, phase and abnormal consumption

The electronics in an LG air conditioner monitor the power supply with a magnifying glass. When the voltage drops, rises too far or enters an improper sequence, the system detects it and protects itself. This is where codes such as CH21, CH22, CH23, CH25, CH28, CH30, CH49 and CH54 appear, all of them related to electrical parameters that have moved outside the safe range.

LG has identified specific protection thresholds in several models, such as input voltages below 140 V or above 300 V in certain configurations, or line spikes exceeding 420 V in other units. These are not laboratory figures included to impress; they mark the point at which the inverter board and compressor begin to suffer. An out-of-range voltage may come from the grid, the installation or the unit’s own electronics.

CH54 deserves separate attention because it may appear after a power cut or following electrical work. It is related to reverse or open phase and, if it persists after resetting the circuit breaker, requires technical inspection. The same family includes warnings for excessive consumption or a locked compressor, such as CH21 and CH22, which often arise when the system is forced to work due to an incorrect load, a mechanical obstruction or a poorly adjusted installation.

Refrigerant and pressure: when there is too little gas or too much resistance

CH38, F4, CH24, CH34, CH35 and CH36 fall into the area of refrigerant and pressure. They are important codes because they do not only indicate poor performance; they also protect the circuit from costly damage. If the refrigerant is not circulating in the correct amount, the air stops cooling as it should and the machine begins to protect itself through internal limits.

CH38 and F4 usually indicate a low refrigerant level. If they appear shortly after an installation or relocation, the most reasonable suspicion is an insufficient charge or a connection that was not properly made. If they arise during normal use, it may be a leak, an unstable power supply or a temporary fault, although the warning recurring shifts the balance toward an inspection with gauges and a check of the pipework.

CH24, CH34, CH35 and CH36 point to abnormal pressure, low pressure or leak detection. These are faults that should be read with caution, because they cannot be solved by cleaning a filter or switching the unit off for a few minutes. When the system detects that the pressure is not right, the message is often the visible tip of a deeper problem: a genuine leak, a poor connection or an obstruction that is disrupting the circuit’s thermal balance.

What to do before assuming a major fault

A complete reset is still the first sensible check in many cases. Unplugging the unit or switching off the circuit breaker for around five minutes helps rule out temporary errors caused by brief power cuts, electrical fluctuations or momentary software lockups. It is a simple step, but very useful for separating noise from the real signal.

After that, it is worth looking around, not just at the code. A dust-filled filter, a blocked grille, an outdoor unit enclosed on a balcony, closed ventilation or a saturated condensate tray can explain many of the most frequent warnings. The surroundings leave very clear traces on these units, and quite often the problem does not originate inside the machine, but in the air that cannot move as it should.

The moment when the alarm appeared also matters. If it came after a storm, a voltage drop, cleaning, a move or a recent installation, the trail points in a different direction. The same is true if the unit started failing in the middle of hot weather with the outdoor unit exposed to the sun and surrounded by dirt. An air conditioner does not work only with electricity; it also has to negotiate every day with dust, temperature, humidity and the space available to it.

How to reduce recurring warnings with basic maintenance

Regularly cleaning the indoor filter is still the most cost-effective measure. During periods of intensive use, doing it every 15 to 30 days helps maintain airflow and reduces the overall strain on the system. When the filter fills up, the unit has to work harder, heats up sooner and eventually triggers protections that could have been avoided with a simple routine.

The outdoor unit also needs to breathe. Dry leaves, dust, lint, small nests or simple obstacles near the grille can trigger overheating and fan errors. Keeping the surrounding area clear is not an aesthetic matter, but an operating requirement. The unit must be able to release heat freely; if it cannot, the electronics detect it immediately.

In new or renovated installations, compatibility between units, the quality of the connections and the power supply deserve a second check. Many errors do not result from wear, but from a detail that was not properly secured on the day of installation. And in a system as sensitive as an inverter split, a small oversight can grow into a major fault.

When the warning speaks clearly, the decision should too

Error codes on an LG air conditioner are neither a punishment nor a technical oddity. They are a diagnostic map showing where coordination has broken down between sensors, fans, boards, refrigerant and the power supply. Read correctly, they make it possible to act before a minor issue turns into a more expensive repair.

The key is not to confuse persistence with mystery. CH04 does not call for the same response as CH25, CH05 does not mean the same thing as CH61, and CH38 is not solved in the same way as CH07. Each warning defines a different area of work, and that difference saves money, time and unnecessary dismantling.

When the unit repeats the same message, the most cautious approach is to stop insisting and move on to an orderly inspection. In air conditioning, precision is worth more than intuition. A unit that gives a clear warning deserves an equally clear response.