HVAC Code Lookup

LG Mini-Split: 2 Flashes

A LG mini-split LED pattern starting with 2 flashes matches 10 documented codes: CH02, CH21, CH22, CH23, CH24, CH25, CH26, CH27, CH28, CH29. Watch the full pattern (short vs. long flashes) to tell them apart — all 10 are explained below.

Code CH02: Indoor unit inlet pipe sensor error

Soft lockoutShown as: Indoor unit LED1 (units place) blinks 2 times

Indoor unit inlet pipe sensor error. The thermistor clamped to the indoor coil's inlet (liquid side) refrigerant pipe is disconnected, shorted or open.

Manual wording: “Indoor unit inlet pipe temperature sensor is disconnected, shorted, or opened.”

Documented for: All LG residential mini-split indoor units

Likely causes, most common first

  1. Sensor mis-wiring or short at the connector
  2. Moisture penetration into the sensor
  3. Bad sensor canning sheath (damaged sensor sheath or insulation)
  4. Sensor housing removed so the sensor is off the pipe
  5. Indoor unit PCB fault (only after the sensor itself checks good)

What you can safely check yourself

  • Turn the system off at the breaker for one minute, then back on, to see if the code clears
  • Check that the indoor unit's front panel and filter access door are fully closed and latched

When to call a technician

The sensor is inside the indoor unit's coil housing. Diagnosing and replacing it is a technician job.

A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Full page for LG code CH02

Code CH21: DC Peak / IPM fault

Hard lockoutShown as: Outdoor LED01 (red) blinks 2 times, LED02 (green) blinks 1 time

DC Peak / IPM fault. The inverter power module in the outdoor unit saw a current or voltage spike from the compressor and shut itself down to protect the board. Most often the system is being asked to work against blocked airflow or is short on refrigerant.

Manual wording: “DC Peak (IPM Fault); Compressor DC voltage was too high”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Overload operation - indoor or outdoor fan restricted, screened or blocked, or a refrigerant cycle issue
  2. Refrigerant leak
  3. Disconnection or short circuit inside the compressor
  4. Compressor failure
  5. Burned parts inside the PCB (IPM failure)

What you can safely check yourself

  • Clear leaves, grass clippings, snow, or anything stacked against or on top of the outdoor unit
  • Check and clean the indoor air filters
  • Make sure the indoor supply and return grilles are open and unblocked
  • Turn the system off at the breaker for three minutes and back on (the boards need three minutes to fully discharge)

When to call a technician

If airflow is clear and CH21 returns, the compressor, its wiring, or the inverter board is failing. That is high-voltage inverter work - 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

Full page for LG code CH21

Code CH22: CT2

Soft lockoutShown as: Outdoor LED01 (red) blinks 2 times, LED02 (green) blinks 2 times

CT2 (current transformer 2) error - the AC input current drawn by the outdoor unit is higher than the limit. Usually the unit is overworking against blocked airflow, or the incoming line voltage is sagging so the unit pulls more amps.

Manual wording: “Current Transformer2 (CT2) error; Alternating current (AC) input too high”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Overload operation - outdoor fan restricted, screened, or blocked
  2. Input voltage error (low voltage)
  3. Burned parts inside the PCB (current sensor section)

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
  • Check the breaker is fully on and not partially tripped

When to call a technician

Measuring input voltage and the board's current sensor is a technician job. If the house voltage is low, an electrician needs to look at the supply.

A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Full page for LG code CH22

Code CH23: DC link voltage error - the DC bus inside the inverter has dropped below about 140 VDC or risen above about 420 VDC

Soft lockoutShown as: Outdoor LED01 (red) blinks 2 times, LED02 (green) blinks 3 times

DC link voltage error - the DC bus inside the inverter has dropped below about 140 VDC or risen above about 420 VDC. Almost always caused by a supply-voltage problem or a failed reactor (choke) in the outdoor unit.

Manual wording: “DC Link Low Voltage (DC Link Voltage is <140VDC) / DC Link High Voltage (DC Link Voltage is >420VDC)”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Input voltage error (low voltage)
  2. Reactor disconnection or bad fastening / reactor wire open
  3. PCB failure in the DC link voltage sensing section

What you can safely check yourself

  • Check the breaker is fully on and not partially tripped
  • Check the outdoor disconnect switch is on
  • If the house has just had a brownout or power outage, turn the system off at the breaker for three minutes and back on

When to call a technician

Checking the reactor, the DC bus, or the power cable is high-voltage work on a charged inverter board. 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

Full page for LG code CH23

Code CH24: Pressure switch / heat sink protection has tripped

Hard lockoutShown as: Outdoor LED1 blinks 2 times, LED2 blinks 4 times

Pressure switch / heat sink protection has tripped. The outdoor unit's protective switch opened, which normally means the system cannot reject heat - blocked coil, blocked airflow, or a refrigerant-side problem.

Manual wording: “24 Pressure Switch / Heater Sink.”

Documented for: LUU090HV ~ LUU420HV and LUU180HHV / LUU240HHV single-zone outdoor units

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
  • Make sure the indoor supply and return grilles are open

When to call a technician

A tripped pressure switch is a protection device doing its job. Never bypass, jumper, or reset a pressure switch - a technician has to find why it tripped.

A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Full page for LG code CH24

Code CH25: AC low / high voltage

Soft lockoutShown as: Outdoor LED01 (red) blinks 2 times, LED02 (green) blinks 5 times

AC low / high voltage. The line voltage feeding the outdoor unit is outside the acceptable range, so the unit shuts down to protect the inverter.

Manual wording: “25 AC Low / High Voltage”

Documented for: LG Multi F / Multi F MAX outdoor units and LS091HSV / LS121HSV single-zone systems

Likely causes, most common first

  1. Voltage to the system is too low or too high

What you can safely check yourself

  • Check the breaker is fully on and not partially tripped
  • Check the outdoor disconnect switch is on
  • If the house has just had a brownout, surge, or power outage, turn the system off at the breaker for three minutes and back on

When to call a technician

If the code returns, an electrician or HVAC technician needs to measure the supply voltage under load. Persistent low or high voltage is a house wiring or utility problem, not a unit problem.

A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Full page for LG code CH25

Code CH26: DC compressor position error

Hard lockoutShown as: Outdoor LED01 (red) blinks 2 times, LED02 (green) blinks 6 times

DC compressor position error. The inverter cannot detect the compressor rotor turning, so the compressor failed to start - it is seized, miswired, or the drive board cannot sense it.

Manual wording: “DC Compressor Position Error (Compressor failed to start properly)”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Poor connection of the compressor connector
  2. Compressor failure (seized, or not providing rotation)
  3. PCB failure

What you can safely check yourself

  • Turn the system off at the breaker for three minutes and back on to allow one clean restart attempt

When to call a technician

CH26 means the compressor is not turning. Checking compressor wiring, winding resistance and insulation is high-voltage technician work.

A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Full page for LG code CH26

Code CH27: PSC / PFC fault - overcurrent in the power factor correction stage between the AC input and the DC converter circuit of the inverter board

Hard lockoutShown as: Outdoor LED01 (red) blinks 2 times, LED02 (green) blinks 7 times

PSC / PFC fault - overcurrent in the power factor correction stage between the AC input and the DC converter circuit of the inverter board.

Manual wording: “PSC / PFC Fault; Input current to inverter compressor PCB is too high”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Overload operation - outdoor fan restricted, screened, or blocked
  2. Bad reactor fastening
  3. Burned PCB internal parts (PSC module)

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
  • Turn the system off at the breaker for three minutes and back on

When to call a technician

The PFC module and reactor are inside the live inverter section of the outdoor unit. 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

Full page for LG code CH27

Code CH28: Inverter compressor DC voltage is too high

Soft lockoutShown as: Outdoor LED1 blinks 2 times, LED2 blinks 8 times

Inverter compressor DC voltage is too high. The DC bus feeding the compressor drive has gone over its limit and the unit shut down to protect itself.

Manual wording: “Inverter compressor DC voltage is too high.”

Documented for: LS091HSV / LS121HSV systems (LSN091HSV / LSN121HSV indoor, LSU091HSV / LSU121HSV outdoor)

Likely causes, most common first

  1. Inverter compressor DC voltage is too high

What you can safely check yourself

  • Check the breaker is fully on and not partially tripped
  • If the house has just had a power surge or outage, turn the system off at the breaker for three minutes and back on

When to call a technician

DC bus overvoltage is measured on a live, charged inverter board - technician only.

A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Source

Full page for LG code CH28

Code CH29: Compressor phase overcurrent - the current into the compressor windings is higher than allowed

Hard lockoutShown as: Outdoor LED01 (red) blinks 2 times, LED02 (green) blinks 9 times

Compressor phase overcurrent - the current into the compressor windings is higher than allowed. Same family of faults as CH21: overload, restricted airflow, low charge, or a failing compressor.

Manual wording: “Compressor phase overcurrent error”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Overload operation - indoor or outdoor fan restricted, screened or blocked, or a refrigerant cycle issue
  2. Refrigerant leak
  3. Disconnection or short circuit inside the compressor
  4. Compressor failure
  5. Burned parts inside the PCB (IPM failure)

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
  • Make sure the indoor supply and return grilles are open and unblocked

When to call a technician

If airflow is clear and CH29 returns, the compressor or inverter board needs a technician. The service manual notes CH29 can also be triggered simply by an overloaded system running in extreme conditions.

A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Full page for LG code CH29

Other LG codes