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 with a distinct role in communicating fault status.
| LED | Color | Role |
|---|---|---|
| Power or operation lamp (indoor) | Green or yellow-green | Running status and fault indication through blink counts |
| Timer or sleep lamp (indoor) | Amber or green | Timer status, filter reminder, and tens-digit encoding during faults |
| PCB power LED (outdoor) | Green | Steady when the outdoor board has power |
| PCB communication LED (outdoor) | Red | Flickering 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 |
|---|---|---|
| Steady green or yellow-green LED | Unit is running normally | No action needed |
| Steady yellow LED (post-2014 models) | Unit is in standby — powered but idle | No action needed |
| Green LED stays on after power-off (older models) | Normal for pre-2014 units — LED remains lit when stopped | No action needed |
| Filter indicator lights up | Filter has logged 2,400 hours since last reset | Clean the filter and press Cancel Reservation three times on the remote |
| E4 on display or brief blink during heating | Defrost cycle — outdoor coil deicing | Wait 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 (CH01-CH12), compressor and inverter faults (CH21-CH38), and multi-split system faults (CH07, CH51). Once you have the CH number, the full LG error code lookup table is on the dedicated LG error code page.
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 |
|---|---|---|
| All indoor units show the same CH code | Outdoor unit or shared wiring | Note the code. Power-cycle the outdoor isolator once |
| One indoor unit shows a code, others run normally | That specific indoor unit — sensor, fan, or wiring | Power-cycle the affected unit. Check the filter and drain |
| CH07 appears on one or more units | Mode conflict — units set to different modes | Set all units to the same mode (all cooling or all fan) |
| CH61 appears | Indoor unit overheating — usually a dirty filter | Turn off for three minutes, clean the filter, and restart |
| Any code in the CH21-CH29 range | Compressor or inverter fault at the outdoor unit | Turn 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 your initial troubleshooting, professional diagnosis is the next step.
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