LG Mini-Split: 3 Flashes
A LG mini-split LED pattern starting with 3 flashes matches 9 documented codes: CH03, CH31, CH32, CH34, CH35, CH36, CH37, CH38, CH39. Watch the full pattern (short vs. long flashes) to tell them apart — all 9 are explained below.
Code CH03: Wired remote controller
Wired remote controller (thermostat) communication error. The indoor unit's control board is not receiving a signal from the wired wall controller. On systems that never had a wired controller, it usually means the controller connector on the board is dirty, wet or shorted.
Manual wording: “Indoor unit PCB is not receiving a signal from the wired remote controller (if installed).”
Documented for: All LG residential mini-split indoor units with an optional wired remote controller
Likely causes, most common first
- Interference between the AC power line and the wired remote control line (wires twisted together or not separated)
- Poor contact or disconnection between the wired remote control DC line and the PCB harness
- PCB harness flooding or corrosion
- Wired remote control fault
- Indoor unit PCB fault
What you can safely check yourself
- Turn the system off at the breaker for one minute, then back on
- If a wired wall controller is installed, check it is not physically damaged or wet
- Check the wall controller's display is lit at all
When to call a technician
Anything past a power cycle means opening the indoor unit or the controller and checking low-voltage wiring - call a technician.
A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- Single Zone Four-Way Ceiling-Cassette Installation Manual (LG Electronics U.S.A., Inc., Single-zone four-way ceiling cassette indoor units with LUU090HV through LUU420HV outdoor units) · checked 2026-08-25
- MULTI F / MULTI F MAX Outdoor Unit Installation Manual (LG Electronics U.S.A., Inc., Multi F and Multi F MAX multi-zone heat pump outdoor units (LMU series) with standard wall-mount, Art Cool, cassette and ducted indoor units) · checked 2026-08-25
- Convertible Mid-Static Ducted LGRED Degree System Installation Manual (LG Electronics U.S.A., Inc., LGRED single-zone convertible mid-static ducted indoor units with LUU180HHV / LUU240HHV outdoor units) · checked 2026-08-25
- Room Air Conditioner SVC Manual (General) - Trouble Shooting Guide with Error Code (LG Electronics, All LG single-zone room air conditioner / mini-split chassis (SW, SB, SC, S4, S5, SH, SA, SJ, SK)) · checked 2026-08-25
Code CH31: Current transformer
Current transformer (CT) reading is too low - the outdoor board is not sensing the current it expects for the compressor speed it commanded.
Manual wording: “Current to the current transformer (CT) thermistor is too low.”
Documented for: LS091HSV / LS121HSV systems (LSN091HSV / LSN121HSV indoor, LSU091HSV / LSU121HSV outdoor)
Likely causes, most common first
- Current to the current transformer (CT) thermistor is too low
What you can safely check yourself
- Turn the system off at the breaker for three minutes and back on
When to call a technician
The current transformer sits on the outdoor inverter board. Diagnosis is technician work.
A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- Defining Common Error Codes - Standard Wall-Mounted High-Efficiency Single Zone Systems (LG Electronics U.S.A. - Commercial Air Conditioning, LS091HSV and LS121HSV systems (LSN091HSV / LSN121HSV indoor units, LSU091HSV / LSU121HSV outdoor units)) · checked 2026-08-25
Code CH32: Inverter compressor discharge pipe
Inverter compressor discharge pipe (D-pipe) temperature is too high. The gas leaving the compressor is overheating, which most often means the outdoor unit cannot reject heat or the system is low on refrigerant.
Manual wording: “Inverter compressor discharge pipe (D-Pipe) temperature is too high”
Documented for: All LG residential mini-split outdoor units
Likely causes, most common first
- Overload operation - outdoor fan restricted, screened, or blocked
- Poor inverter compressor discharge sensor
- Refrigerant leakage (insufficient charge)
- EEV connector displaced or poor EEV (electronic expansion valve) assembly
What you can safely check yourself
- Clear leaves, grass clippings, snow, or debris away from the outdoor coil and fan
- Remove anything stacked against or on top of the outdoor unit
- Check and clean the indoor air filters
- Give the unit time to cool down, then turn it off at the breaker for three minutes and back on
When to call a technician
If airflow is clear and CH32 returns, the system is likely low on refrigerant or the expansion valve is misbehaving. Both require a licensed technician with gauges.
A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- MULTI F / MULTI F MAX Outdoor Unit Installation Manual (LG Electronics U.S.A., Inc., Multi F and Multi F MAX multi-zone heat pump outdoor units (LMU series) with standard wall-mount, Art Cool, cassette and ducted indoor units) · checked 2026-08-25
- Single Zone Four-Way Ceiling-Cassette Installation Manual (LG Electronics U.S.A., Inc., Single-zone four-way ceiling cassette indoor units with LUU090HV through LUU420HV outdoor units) · checked 2026-08-25
- Convertible Mid-Static Ducted LGRED Degree System Installation Manual (LG Electronics U.S.A., Inc., LGRED single-zone convertible mid-static ducted indoor units with LUU180HHV / LUU240HHV outdoor units) · checked 2026-08-25
- Defining Common Error Codes - Standard Wall-Mounted High-Efficiency Single Zone Systems (LG Electronics U.S.A. - Commercial Air Conditioning, LS091HSV and LS121HSV systems (LSN091HSV / LSN121HSV indoor units, LSU091HSV / LSU121HSV outdoor units)) · checked 2026-08-25
- Room Air Conditioner SVC Manual (General) - Trouble Shooting Guide with Error Code (LG Electronics, All LG single-zone room air conditioner / mini-split chassis (SW, SB, SC, S4, S5, SH, SA, SJ, SK)) · checked 2026-08-25
Code CH34: High pressure sensor error
High pressure sensor error (high) - the outdoor unit is reading discharge pressure above its limit. Typically the condenser cannot reject heat, or the charge is off.
Manual wording: “High pressure sensor error (high)”
Documented for: LG single-zone room air conditioner / mini-split outdoor units fitted with pressure sensors
Likely causes, most common first
- Overload operation - outdoor fan restricted, screened, or blocked
- Refrigerant leakage (insufficient charge)
- Bad connection of the pressure sensor
- Bad compressor sensor
- Bad PCB
What you can safely check yourself
- Clear leaves, grass clippings, snow, or debris away from the outdoor coil and fan
- Remove anything stacked against or on top of the outdoor unit
- Check and clean the indoor air filters
When to call a technician
Pressure faults require gauges and a licensed technician. Do not open, tighten or bypass anything on the refrigerant side.
A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- Room Air Conditioner SVC Manual (General) - Trouble Shooting Guide with Error Code (LG Electronics, All LG single-zone room air conditioner / mini-split chassis (SW, SB, SC, S4, S5, SH, SA, SJ, SK)) · checked 2026-08-25
Code CH35: Low pressure error - suction pressure has dropped below the recommended limit
Low pressure error - suction pressure has dropped below the recommended limit. Usually low refrigerant charge, a restriction, or badly blocked indoor airflow.
Manual wording: “Low Pressure Error; Pressure dropped below recommended limits”
Documented for: All LG residential mini-split outdoor units fitted with pressure sensors
Likely causes, most common first
- Overload operation - outdoor fan restricted, screened, or blocked
- Refrigerant leakage (insufficient charge)
- Bad connection of the pressure sensor
- Bad compressor sensor
- Bad PCB
What you can safely check yourself
- Check and clean the indoor air filters
- Make sure the indoor supply and return grilles are open and unblocked
- Clear leaves, grass clippings, snow, or debris away from the outdoor coil
When to call a technician
Low pressure almost always means the system has lost refrigerant. Refrigerant work is EPA-regulated - call a licensed technician.
A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- MULTI F / MULTI F MAX Outdoor Unit Installation Manual (LG Electronics U.S.A., Inc., Multi F and Multi F MAX multi-zone heat pump outdoor units (LMU series) with standard wall-mount, Art Cool, cassette and ducted indoor units) · checked 2026-08-25
- Single Zone Four-Way Ceiling-Cassette Installation Manual (LG Electronics U.S.A., Inc., Single-zone four-way ceiling cassette indoor units with LUU090HV through LUU420HV outdoor units) · checked 2026-08-25
- Convertible Mid-Static Ducted LGRED Degree System Installation Manual (LG Electronics U.S.A., Inc., LGRED single-zone convertible mid-static ducted indoor units with LUU180HHV / LUU240HHV outdoor units) · checked 2026-08-25
- Room Air Conditioner SVC Manual (General) - Trouble Shooting Guide with Error Code (LG Electronics, All LG single-zone room air conditioner / mini-split chassis (SW, SB, SC, S4, S5, SH, SA, SJ, SK)) · checked 2026-08-25
Code CH36: Refrigerant leakage detection
Refrigerant leakage detection. The outdoor unit's control logic has concluded the system is short on refrigerant.
Manual wording: “Refrigerant leakage detection”
Documented for: LG single-zone room air conditioner / mini-split outdoor units with leak detection logic
Likely causes, most common first
- Pipe break damage
- Bad connection of the pipe (flare joints)
- Pipe damage due to corrosion
- Corrosion damage of the heat exchanger
- Compressor damage (crack)
- EEV body clogging
- Refrigerant shortage, including too little refrigerant added at install for the line length
What you can safely check yourself
- Turn the system off so the compressor is not running short of refrigerant until a technician can look at it
When to call a technician
Refrigerant leak repair and recharging are EPA-regulated and require a licensed technician with recovery equipment. Do not add refrigerant yourself.
A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- Room Air Conditioner SVC Manual (General) - Trouble Shooting Guide with Error Code (LG Electronics, All LG single-zone room air conditioner / mini-split chassis (SW, SB, SC, S4, S5, SH, SA, SJ, SK)) · checked 2026-08-25
Code CH37: Compression ratio limit exceeded
Compression ratio limit exceeded. The ratio between discharge and suction pressure is outside the compressor's safe envelope, so the unit stops. Points at a restriction, a closed service valve, or a charge problem.
Manual wording: “Failure compressing ratio”
Documented for: LG single-zone room air conditioner / mini-split outdoor units
Likely causes, most common first
- Overload operation - outdoor fan restricted, screened, or blocked
- Service (SVC) valve locked or left closed
- Bad compressor sensor
- EEV connector displaced or poor EEV assembly
- EEV body clogging
- Refrigerant leakage (insufficient charge)
- Refrigerant overcharge
What you can safely check yourself
- Clear leaves, grass clippings, snow, or debris away from the outdoor coil and fan
- Check and clean the indoor air filters
When to call a technician
A closed service valve, a clogged expansion valve, or an incorrect charge all need a licensed technician with gauges. Never operate the service valves yourself.
A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- Room Air Conditioner SVC Manual (General) - Trouble Shooting Guide with Error Code (LG Electronics, All LG single-zone room air conditioner / mini-split chassis (SW, SB, SC, S4, S5, SH, SA, SJ, SK)) · checked 2026-08-25
Code CH38: Refrigerant leakage detection - the system is low on refrigerant
Refrigerant leakage detection - the system is low on refrigerant. LG's consumer support page states plainly that CH38 means the air conditioner is low on refrigerant (gas).
Manual wording: “Refrigerant leakage detection”
Documented for: LG residential mini-split outdoor units with refrigerant leak detection (including LSU363HLV-class dual inverter units)
Likely causes, most common first
- Pipe break damage
- Bad connection of the pipe (flare joints)
- Pipe damage due to corrosion
- Corrosion damage of the heat exchanger
- Compressor damage (crack)
- EEV body clogging
- Refrigerant shortage, including too little refrigerant added at install for the line length
What you can safely check yourself
- Turn the system off so the compressor is not running short of refrigerant until a technician can look at it
When to call a technician
A leak has to be found, repaired, and the system evacuated and recharged by weight. That is EPA-regulated work for a licensed technician - topping it off without finding the leak just repeats the failure.
A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- Room Air Conditioner SVC Manual (General) - Trouble Shooting Guide with Error Code (LG Electronics, All LG single-zone room air conditioner / mini-split chassis (SW, SB, SC, S4, S5, SH, SA, SJ, SK)) · checked 2026-08-25
- LG Air Conditioner - Guide to Error Codes (LG USA Support help library) (LG Electronics U.S.A., Inc., LG residential single-split and multi-split air conditioners / heat pumps) · checked 2026-08-25
Code CH39: Communication error between the PFC MICOM and the inverter MICOM - the two microcontrollers on the outdoor unit's power board have lost contact with each other
Communication error between the PFC MICOM and the inverter MICOM - the two microcontrollers on the outdoor unit's power board have lost contact with each other.
Manual wording: “Communication Error between PFC MICOM and Inverter MICOM”
Documented for: LG Multi F / Multi F MAX outdoor units
What you can safely check yourself
- Turn the system off at the breaker for three minutes and back on
When to call a technician
This is an internal fault between processors on the outdoor inverter board. A technician has to diagnose and usually replace the board.
A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- MULTI F / MULTI F MAX Outdoor Unit Installation Manual (LG Electronics U.S.A., Inc., Multi F and Multi F MAX multi-zone heat pump outdoor units (LMU series) with standard wall-mount, Art Cool, cassette and ducted indoor units) · checked 2026-08-25