LG Aircon Blinking Light Guide
LG units use a CH-prefix error code system. On models with a display, the code shows directly. On LED-only units, two indicator lights encode the code through counted blinks. Knowing how to read both formats is the first step before deciding what to do next.
What Each Indicator Light On An LG Indoor Unit Does
LG indoor units use two LEDs on the panel plus a pair of diagnostic LEDs on the outdoor PCB. Each serves a distinct role in communicating fault status.
| LED | Color | Role |
|---|---|---|
| LEDPower or operation lamp (indoor) | ColorGreen or yellow-green | RoleRunning status and fault indication through blink counts |
| LEDTimer or sleep lamp (indoor) | ColorAmber or green | RoleTimer status, filter reminder, and tens-digit encoding during faults |
| LEDPCB power LED (outdoor) | ColorGreen | RoleSteady when the outdoor board has power |
| LEDPCB communication LED (outdoor) | ColorRed | RoleFlickering is normal. Steady or absent means communication fault |
LG indoor panel LEDs and CH code indication
Most LG wall-mounted units in Singapore (Alpha and Artcool+ series) have two LEDs on the front panel. The power or operation LED. Green on most models, yellow-green when running on post-2014 units. Shows running status. A secondary LED handles timer, sleep, and filter cleaning reminders.
On units with a digital display or wired remote, error codes appear directly as CH followed by a two-digit number. On LED-only units without a display, the two LEDs encode the error code through counted blinks. The power LED blinks for the units digit and the secondary LED blinks for the tens digit. Two blinks on the power LED plus one blink on the secondary LED means CH21.
LG outdoor unit PCB diagnostic LEDs
The outdoor unit PCB has its own pair of diagnostic LEDs. A steady green LED means the board has power. A flickering red LED means the board is receiving communication from the indoor unit. A steady (non-flickering) red LED means communication has stopped. No red light at all points to an outdoor PCB fault.
Normal LG Indicator Light Behavior: Not A Fault
A steady green or yellow-green LED during operation is normal. On post-2014 models, the LED turns yellow when the unit is in standby (powered but not running). Older models keep the green LED lit even when the unit is off. This is not a fault.
The filter indicator lights up after roughly 2,400 hours of cumulative operation. It is a maintenance reminder, not an error. Clean the filter, then press the Cancel Reservation or Set/Release button on the remote three times to reset it.
During heating mode, an E4 display or brief LED blink can indicate a defrost cycle. The unit pauses to deice the outdoor coil and resumes automatically. This is uncommon in Singapore unless the outdoor coil is heavily soiled or the unit is running in dry mode for extended periods.
| Pattern | What is happening | What to do |
|---|---|---|
| PatternSteady green or yellow-green LED | What is happeningUnit is running normally | What to doNo action needed |
| PatternSteady yellow LED (post-2014 models) | What is happeningUnit is in standby. Powered but idle | What to doNo action needed |
| PatternGreen LED stays on after power-off (older models) | What is happeningNormal for pre-2014 units. LED remains lit when stopped | What to doNo action needed |
| PatternFilter indicator lights up | What is happeningFilter has logged 2,400 hours since last reset | What to doClean the filter and press Cancel Reservation three times on the remote |
| PatternE4 on display or brief blink during heating | What is happeningDefrost cycle. Outdoor coil deicing | What to doWait for the cycle to finish |
How To Read The CH Error Code From Your LG Unit
LG units surface the CH fault code either directly on the display or through a two-LED blink sequence, depending on the model.
Display models versus LED-only models
When a fault occurs, LG units display a CH code followed by a two-digit number. On display-equipped models, the code shows directly on the panel or wired remote. On LED-only models, count the blinks on each LED, the power LED gives the units digit and the secondary LED gives the tens digit, with a pause between each sequence.
Resetting after a fault and outdoor PCB codes
If multiple faults occur at the same time, the lowest-numbered code displays first. After that fault is resolved, the next code appears. To reset after resolving the issue, turn off the unit at the circuit breaker, wait five minutes, and restore power. If the code returns, the underlying fault persists.
For the outdoor unit PCB, the red LED (LED01G) blinks for the tens digit and the green LED (LED02G) blinks for the units digit. This requires opening the outdoor unit cover, so it is mainly useful for technicians during on-site diagnosis.
Once you have the code
LG's CH code range covers indoor sensor faults, compressor and inverter protection, and multi-split faults such as CH07 and CH51. Once you have the CH number, use the LG error codes lookup to confirm the fault category and next step.
How Multi-split LG Systems Display CH Fault Codes
The table below maps common multi-split fault scenarios to their likely source and the appropriate first response.
| Scenario | Likely fault location | Next step |
|---|---|---|
| ScenarioAll indoor units show the same CH code | Likely fault locationOutdoor unit or shared wiring | Next stepNote the code. Power-cycle the outdoor isolator once |
| ScenarioOne indoor unit shows a code, others run normally | Likely fault locationThat specific indoor unit. Sensor, fan, or wiring | Next stepPower-cycle the affected unit. Check the filter and drain |
| ScenarioCH07 appears on one or more units | Likely fault locationMode conflict. Units set to different modes | Next stepSet all units to the same mode (all cooling or all fan) |
| ScenarioCH61 appears | Likely fault locationIndoor unit overheating. Usually a dirty filter | Next stepTurn off for three minutes, clean the filter, and restart |
| ScenarioAny code in the CH21-CH29 range | Likely fault locationCompressor or inverter fault at the outdoor unit | Next stepTurn off immediately. Call a technician |
How faults appear across multiple indoor units
LG multi-split systems (System 2, 3, and 4) are common in Singapore HDB and condo installations, particularly the Alpha and Artcool+ lines. When the outdoor unit faults, all connected indoor units display the same error code. They share the same communication and refrigerant circuit.
CH07 (mode conflict) is exclusive to multi-split setups. It appears when one indoor unit is set to cooling while another requests a different mode. All units must operate in the same mode. CH51 (unit mismatch) means the connected indoor units exceed the outdoor unit's capacity or are incompatible models.
Self-service steps before calling a technician
For any CH21-series code (compressor, inverter, overcurrent), turn off the unit and call a technician. For CH05 or CH53 (communication errors), try a five-minute power reset first. For CH61 (indoor temperature too high), clean the filters thoroughly. This is the most common self-fixable code. If any code returns after initial troubleshooting, professional diagnosis is needed.
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