HVAC Code Lookup

LG fault codes

48 documented codes for LG mini-splits, each cited to the manufacturer's own manual. Find your code in the table, then jump to what it means, the likely causes, what you can safely check, and when to call a technician.

LG uses one CH## error-code set across its residential ductless line: single-zone wall-mount (LS/LA/LAN indoor + LSU/LAU outdoor), Art Cool, ceiling cassette, ducted/LGRED, and the Multi F / Multi F MAX multi-zone systems (LMU outdoor units). CH01-CH12 are indoor-unit faults and CH21-CH73 are outdoor-unit faults, except CH05/CH53 which are the two ends of the same indoor-to-outdoor communication fault. LG's commercial Multi V VRF equipment uses the same low numbers plus a much larger extended code set that is NOT covered here.

Looking it up by flash count?

If you counted LED flashes rather than reading a code number, these are the codes that start with that many flashes:

  • 1 flashes: CH01 (Indoor unit room), CH10 (Indoor unit BLDC fan motor lock), CH12 (Indoor unit middle pipe sensor error)
  • 2 flashes: CH02 (Indoor unit inlet pipe sensor error), CH21 (DC Peak / IPM fault), CH22 (CT2), CH23 (DC link voltage error - the DC bus inside the inverter has dropped below about 140 VDC or risen above about 420 VDC), CH24 (Pressure switch / heat sink protection has tripped), CH25 (AC low / high voltage), CH26 (DC compressor position error), CH27 (PSC / PFC fault - overcurrent in the power factor correction stage between the AC input and the DC converter circuit of the inverter board), CH28 (Inverter compressor DC voltage is too high), CH29 (Compressor phase overcurrent - the current into the compressor windings is higher than allowed)
  • 3 flashes: CH03 (Wired remote controller), CH31 (Current transformer), CH32 (Inverter compressor discharge pipe), CH34 (High pressure sensor error), CH35 (Low pressure error - suction pressure has dropped below the recommended limit), CH36 (Refrigerant leakage detection), CH37 (Compression ratio limit exceeded), CH38 (Refrigerant leakage detection - the system is low on refrigerant), 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)
  • 4 flashes: CH04 (Drain pump / float switch error), CH40 (Current transformer), CH41 (Inverter compressor discharge pipe), CH42 (Low pressure sensor open or short), CH43 (High pressure sensor is disconnected or shorted out), CH44 (Outdoor air), CH45 (Mid-pipe thermistor of the outdoor unit condenser coil is disconnected or shorted out), CH46 (Outdoor unit suction pipe thermistor is disconnected or shorted out), CH48 (Outdoor unit condenser coil outlet)
  • 5 flashes: CH05 (Communication error between the indoor unit and the outdoor unit), CH51 (Over capacity / combination ratio out of range), CH53 (Communication failure from the outdoor unit to the indoor unit), CH54 (Open phase / reverse phase error - the outdoor unit's incoming power is missing a leg or wired in the wrong order)
  • 6 flashes: CH06 (Indoor unit outlet pipe sensor error), CH60 (Outdoor unit PCB EEPROM check sum error), CH61 (Outdoor unit condenser coil pipe temperature is too high), CH62 (Outdoor unit inverter compressor PCB heat sink temperature is too high), CH63 (Condenser coil pipe thermistor temperature is too low), CH65 (Heat sink thermistor is disconnected or shorted out), CH67 (Outdoor BLDC fan motor lock error)
  • 7 flashes: CH07 (Different mode operation error), CH72 (Four-way), CH73 (PSC / PFC overcurrent error detected in software - the outdoor unit's power factor correction stage saw a current peak beyond its limit)
  • 9 flashes: CH09 (Indoor unit EEPROM error), CH93 (Indoor / outdoor unit communication error)

Mini-Split codes

CodeMeaningSeverity
CH00No errorStatus
CH01Indoor unit LED1 (units place) blinks 1 timeIndoor unit roomSoft lockout
CH02Indoor unit LED1 (units place) blinks 2 timesIndoor unit inlet pipe sensor errorSoft lockout
CH03Indoor unit LED1 (units place) blinks 3 timesWired remote controllerSoft lockout
CH04Indoor unit LED1 (units place) blinks 4 timesDrain pump / float switch errorSoft lockout
CH05Indoor unit LED1 (units place) blinks 5 timesCommunication error between the indoor unit and the outdoor unitSoft lockout
CH06Indoor unit LED1 (units place) blinks 6 timesIndoor unit outlet pipe sensor errorSoft lockout
CH07Indoor unit LED1 (units place) blinks 7 timesDifferent mode operation errorWarning
CH09Indoor unit LED1 (units place) blinks 9 timesIndoor unit EEPROM errorHard lockout
CH10Indoor unit LED2 (tens place) blinks 1 time, LED1 does not blinkIndoor unit BLDC fan motor lockSoft lockout
CH12Indoor unit LED1 (units place) blinks 2 times and LED2 (tens place) blinks 1 timeIndoor unit middle pipe sensor errorSoft lockout
CH21Outdoor LED01 (red) blinks 2 times, LED02 (green) blinks 1 timeDC Peak / IPM faultHard lockout
CH22Outdoor LED01 (red) blinks 2 times, LED02 (green) blinks 2 timesCT2Soft lockout
CH23Outdoor LED01 (red) blinks 2 times, LED02 (green) blinks 3 timesDC link voltage error - the DC bus inside the inverter has dropped below about 140 VDC or risen above about 420 VDCSoft lockout
CH24Outdoor LED1 blinks 2 times, LED2 blinks 4 timesPressure switch / heat sink protection has trippedHard lockout
CH25Outdoor LED01 (red) blinks 2 times, LED02 (green) blinks 5 timesAC low / high voltageSoft lockout
CH26Outdoor LED01 (red) blinks 2 times, LED02 (green) blinks 6 timesDC compressor position errorHard lockout
CH27Outdoor LED01 (red) blinks 2 times, LED02 (green) blinks 7 timesPSC / PFC fault - overcurrent in the power factor correction stage between the AC input and the DC converter circuit of the inverter boardHard lockout
CH28Outdoor LED1 blinks 2 times, LED2 blinks 8 timesInverter compressor DC voltage is too highSoft lockout
CH29Outdoor LED01 (red) blinks 2 times, LED02 (green) blinks 9 timesCompressor phase overcurrent - the current into the compressor windings is higher than allowedHard lockout
CH31Outdoor LED1 blinks 3 times, LED2 blinks 1 timeCurrent transformerSoft lockout
CH32Outdoor LED01 (red) blinks 3 times, LED02 (green) blinks 2 timesInverter compressor discharge pipeSoft lockout
CH34Outdoor LED1 blinks 3 times, LED2 blinks 4 times (2-LED type; the service manual pairs CH34 with CH35 in one row)High pressure sensor errorSoft lockout
CH35Outdoor LED01 (red) blinks 3 times, LED02 (green) blinks 5 timesLow pressure error - suction pressure has dropped below the recommended limitSoft lockout
CH36Outdoor LED1 blinks 3 times, LED2 blinks 6 times (2-LED type; service manual lists this row as '36 (38)')Refrigerant leakage detectionHard lockout
CH37Outdoor LED1 blinks 3 times, LED2 blinks 7 times (2-LED type)Compression ratio limit exceededSoft lockout
CH38Outdoor LED1 blinks 3 times, LED2 blinks 6 times (2-LED type; service manual lists this row as '36 (38)')Refrigerant leakage detection - the system is low on refrigerantHard lockout
CH39Outdoor LED01 (red) blinks 3 times, LED02 (green) blinks 9 timesCommunication error between the PFC MICOM and the inverter MICOM - the two microcontrollers on the outdoor unit's power board have lost contact with each otherSoft lockout
CH40Outdoor LED01 (red) blinks 4 times, LED02 (green) does not blinkCurrent transformerHard lockout
CH41Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 1 timeInverter compressor discharge pipeSoft lockout
CH42Outdoor LED1 blinks 4 times, LED2 blinks 2 times (2-LED type)Low pressure sensor open or shortSoft lockout
CH43Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 3 timesHigh pressure sensor is disconnected or shorted outSoft lockout
CH44Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 4 timesOutdoor airSoft lockout
CH45Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 5 timesMid-pipe thermistor of the outdoor unit condenser coil is disconnected or shorted outSoft lockout
CH46Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 6 timesOutdoor unit suction pipe thermistor is disconnected or shorted outSoft lockout
CH48Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 8 timesOutdoor unit condenser coil outletSoft lockout
CH51Outdoor LED01 (red) blinks 5 times, LED02 (green) blinks 1 timeOver capacity / combination ratio out of rangeHard lockout
CH53Outdoor LED01 (red) blinks 5 times, LED02 (green) blinks 3 timesCommunication failure from the outdoor unit to the indoor unitSoft lockout
CH54Outdoor LED01 (red) blinks 5 times, LED02 (green) blinks 4 timesOpen phase / reverse phase error - the outdoor unit's incoming power is missing a leg or wired in the wrong orderHard lockout
CH60Outdoor LED01 (red) blinks 6 times, LED02 (green) does not blinkOutdoor unit PCB EEPROM check sum errorHard lockout
CH61Outdoor LED01 (red) blinks 6 times, LED02 (green) blinks 1 timeOutdoor unit condenser coil pipe temperature is too highSoft lockout
CH62Outdoor LED01 (red) blinks 6 times, LED02 (green) blinks 2 timesOutdoor unit inverter compressor PCB heat sink temperature is too highSoft lockout
CH63Outdoor LED1 blinks 6 times, LED2 blinks 3 timesCondenser coil pipe thermistor temperature is too lowSoft lockout
CH65Outdoor LED01 (red) blinks 6 times, LED02 (green) blinks 5 timesHeat sink thermistor is disconnected or shorted outSoft lockout
CH67Outdoor LED01 (red) blinks 6 times, LED02 (green) blinks 7 timesOutdoor BLDC fan motor lock errorHard lockout
CH72Outdoor LED1 blinks 7 times, LED2 blinks 2 times (2-LED type)Four-waySoft lockout
CH73Outdoor LED01 (red) blinks 7 times, LED02 (green) blinks 3 timesPSC / PFC overcurrent error detected in software - the outdoor unit's power factor correction stage saw a current peak beyond its limitSoft lockout
CH93Indoor / outdoor unit communication errorSoft lockout

LG mini-split code CH00: No error

Status

No error. CH00 is the normal 'no fault stored' reading, not a failure. It shows up when a technician or a wired remote queries the system and nothing is wrong.

Manual wording: “00 No error”

Documented for: All LG residential single-zone and Multi F / Multi F MAX mini-splits

When to call a technician

No service needed - CH00 means the system is reporting no error.

Source

LG mini-split code CH01: Indoor unit room

Soft lockoutShown as: Indoor unit LED1 (units place) blinks 1 time

Indoor unit room (return air) temperature sensor error. The thermistor that reads the room temperature is disconnected, shorted or open, so the indoor unit cannot tell how warm the room is and shuts down.

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

Documented for: All LG residential mini-split indoor units (wall-mount, Art Cool, cassette, ducted)

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 out of its holder
  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

A thermistor that reads open or shorted has to be measured and replaced by a technician. There is no homeowner adjustment for this code.

Sources

LG mini-split 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.

Sources

LG mini-split code CH03: Wired remote controller

Soft lockoutShown as: Indoor unit LED1 (units place) blinks 3 times

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

  1. Interference between the AC power line and the wired remote control line (wires twisted together or not separated)
  2. Poor contact or disconnection between the wired remote control DC line and the PCB harness
  3. PCB harness flooding or corrosion
  4. Wired remote control fault
  5. 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.

Sources

LG mini-split code CH04: Drain pump / float switch error

Soft lockoutShown as: Indoor unit LED1 (units place) blinks 4 times

Drain pump / float switch error. Condensate is backing up inside the indoor unit - the float switch has tripped or the drain pump is not clearing water. LG's consumer page describes it as water formed inside the indoor unit not being drained.

Manual wording: “Drain pump malfunction.”

Documented for: LG mini-split indoor units fitted with a drain pump or float switch (cassette, ducted, and wall-mount units with an accessory pump)

Likely causes, most common first

  1. Drain pump fault
  2. Drain hose clogging
  3. Float switch fault
  4. Missing or badly seated short key (jumper) on the indoor PCB float-switch connector, on models that do not use a float switch

What you can safely check yourself

  • Follow the condensate drain line to where it exits and check for a clog, kink, or standing water
  • Check the drain line is not pinched, crushed, or running uphill
  • Clear any obvious blockage at the outdoor end of the drain line
  • Turn the system off at the breaker for one minute and back on after clearing an obvious drain blockage

When to call a technician

If the drain line is clear and CH04 returns, the drain pump or float switch inside the unit has failed and needs a technician. Do not remove or bypass the float switch - it is what stops the unit flooding your ceiling or wall.

Sources

LG mini-split code CH05: Communication error between the indoor unit and the outdoor unit

Soft lockoutShown as: Indoor unit LED1 (units place) blinks 5 times

Communication error between the indoor unit and the outdoor unit. The indoor unit's control board is not receiving a signal from the outdoor unit. This is the single most common LG mini-split code and it usually means the outdoor unit has no power or the interconnecting wiring is wrong or loose.

Manual wording: “Indoor unit PCB is not receiving signal from outdoor unit.”

Documented for: All LG residential mini-splits, single-zone and multi-zone

Likely causes, most common first

  1. No power on the indoor unit
  2. Indoor/outdoor unit power connection error, or the communication line was never installed
  3. Improper connection at the terminal block for the communication wire
  4. Improper wiring of the communication L-N wire between indoor and outdoor units
  5. Communication error caused by external electrical noise
  6. Indoor/outdoor communication circuit parts burned, or no power due to a burned indoor or outdoor PCB

What you can safely check yourself

  • Check the breakers for BOTH the indoor and outdoor unit are on and not tripped
  • Check the outdoor disconnect switch next to the condenser is switched on
  • Turn the system off at the breaker for one minute, then back on

When to call a technician

If power is confirmed on at both units and CH05 stays, the interconnecting communication wiring or one of the control boards is at fault. Terminal-block and low-voltage work is a technician job.

Sources

LG mini-split code CH06: Indoor unit outlet pipe sensor error

Soft lockoutShown as: Indoor unit LED1 (units place) blinks 6 times

Indoor unit outlet pipe sensor error. The thermistor on the indoor coil's outlet (gas side) refrigerant pipe is disconnected, shorted or open.

Manual wording: “Indoor unit outlet 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 sits on the refrigerant piping inside the indoor unit. Replacing it is a technician job.

Sources

LG mini-split code CH07: Different mode operation error

WarningShown as: Indoor unit LED1 (units place) blinks 7 times

Different mode operation error. On a multi-zone system, one indoor unit is calling for heating while another on the same outdoor unit is calling for cooling or dry. One outdoor unit can only do one thing at a time, so the conflicting zones are blocked. LG's consumer page describes it as the units being set to different operating modes.

Manual wording: “07 Different mode operation error”

Documented for: LG Multi F / Multi F MAX multi-zone systems (LMU outdoor units with two or more indoor units)

Likely causes, most common first

  1. One indoor unit set to heating while another indoor unit on the same outdoor unit is set to cooling or dehumidify
  2. A zone left running in a stale mode from a previous season

What you can safely check yourself

  • Set every indoor unit connected to the same outdoor unit to the same mode - all cooling/dry, or all heating
  • Turn off any indoor unit that does not need to run
  • After all zones agree on a mode, the code should clear on its own

When to call a technician

If every indoor unit is already in the same mode and CH07 keeps coming back, one indoor unit is sending a bad mode signal and needs a technician.

Sources

LG mini-split code CH09: Indoor unit EEPROM error

Hard lockoutShown as: Indoor unit LED1 (units place) blinks 9 times

Indoor unit EEPROM error. The memory chip on the indoor control board that stores the unit's model and setup data is unreadable, so the board does not know what unit it is controlling.

Manual wording: “Indoor unit EEPROM serial number marked on is 0 or FFFFFF.”

Documented for: All LG residential mini-split indoor units

Likely causes, most common first

  1. Poor connection of the option PCB
  2. Indoor unit EEPROM serial number reads 0 or FFFFFF (corrupted or blank memory chip)

What you can safely check yourself

  • Turn the system off at the breaker for one minute, then back on

When to call a technician

CH09 is a control board / memory chip fault. The service manual's only remedy is to check the option PCB connection and replace the board - a technician job.

Sources

LG mini-split code CH10: Indoor unit BLDC fan motor lock

Soft lockoutShown as: Indoor unit LED2 (tens place) blinks 1 time, LED1 does not blink

Indoor unit BLDC fan motor lock. The indoor blower is not turning when the board commands it - either something is physically jamming it, the motor plug is loose, or the motor has failed.

Manual wording: “Indoor unit fan motor connection is disconnected. Indoor unit fan motor lock has failed.”

Documented for: All LG residential mini-split indoor units with BLDC fan motors

Likely causes, most common first

  1. Fan locked by physical force (foreign object stuck in the motor or blower wheel)
  2. Poor connection of the motor connector
  3. Motor failure
  4. PCB failure

What you can safely check yourself

  • Turn the unit off at the breaker, then look for anything obviously blocking the indoor fan or the air path
  • Check and clean the indoor air filters
  • Make sure the supply louvers are not jammed shut or blocked by furniture or curtains
  • Restore power and try once more

When to call a technician

If nothing is jamming the blower and CH10 returns, the fan motor or the control board has failed. Do not reach into the blower housing on a powered unit.

Sources

LG mini-split code CH12: Indoor unit middle pipe sensor error

Soft lockoutShown as: Indoor unit LED1 (units place) blinks 2 times and LED2 (tens place) blinks 1 time

Indoor unit middle pipe sensor error. The thermistor on the middle of the indoor coil is disconnected or shorted out.

Manual wording: “Indoor unit middle pipe thermistor has disconnected or has shorted out.”

Documented for: LSN091HSV / LSN121HSV and other LG single-zone indoor units fitted with a middle pipe sensor

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

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

When to call a technician

Thermistor replacement inside the indoor coil housing is a technician job.

Sources

LG mini-split 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.

Sources

LG mini-split 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.

Sources

LG mini-split 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.

Sources

LG mini-split 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.

Sources

LG mini-split 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.

Sources

LG mini-split 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.

Sources

LG mini-split 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.

Sources

LG mini-split 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.

Source

LG mini-split 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.

Sources

LG mini-split code CH31: Current transformer

Soft lockoutShown as: Outdoor LED1 blinks 3 times, LED2 blinks 1 time

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

  1. 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.

Source

LG mini-split code CH32: Inverter compressor discharge pipe

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

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

  1. Overload operation - outdoor fan restricted, screened, or blocked
  2. Poor inverter compressor discharge sensor
  3. Refrigerant leakage (insufficient charge)
  4. 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.

Sources

LG mini-split code CH34: High pressure sensor error

Soft lockoutShown as: Outdoor LED1 blinks 3 times, LED2 blinks 4 times (2-LED type; the service manual pairs CH34 with CH35 in one row)

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

  1. Overload operation - outdoor fan restricted, screened, or blocked
  2. Refrigerant leakage (insufficient charge)
  3. Bad connection of the pressure sensor
  4. Bad compressor sensor
  5. 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.

Source

LG mini-split code CH35: Low pressure error - suction pressure has dropped below the recommended limit

Soft lockoutShown as: Outdoor LED01 (red) blinks 3 times, LED02 (green) blinks 5 times

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

  1. Overload operation - outdoor fan restricted, screened, or blocked
  2. Refrigerant leakage (insufficient charge)
  3. Bad connection of the pressure sensor
  4. Bad compressor sensor
  5. 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.

Sources

LG mini-split code CH36: Refrigerant leakage detection

Hard lockoutShown as: Outdoor LED1 blinks 3 times, LED2 blinks 6 times (2-LED type; service manual lists this row as '36 (38)')

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

  1. Pipe break damage
  2. Bad connection of the pipe (flare joints)
  3. Pipe damage due to corrosion
  4. Corrosion damage of the heat exchanger
  5. Compressor damage (crack)
  6. EEV body clogging
  7. 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.

Source

LG mini-split code CH37: Compression ratio limit exceeded

Soft lockoutShown as: Outdoor LED1 blinks 3 times, LED2 blinks 7 times (2-LED type)

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

  1. Overload operation - outdoor fan restricted, screened, or blocked
  2. Service (SVC) valve locked or left closed
  3. Bad compressor sensor
  4. EEV connector displaced or poor EEV assembly
  5. EEV body clogging
  6. Refrigerant leakage (insufficient charge)
  7. 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.

Source

LG mini-split code CH38: Refrigerant leakage detection - the system is low on refrigerant

Hard lockoutShown as: Outdoor LED1 blinks 3 times, LED2 blinks 6 times (2-LED type; service manual lists this row as '36 (38)')

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

  1. Pipe break damage
  2. Bad connection of the pipe (flare joints)
  3. Pipe damage due to corrosion
  4. Corrosion damage of the heat exchanger
  5. Compressor damage (crack)
  6. EEV body clogging
  7. 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.

Sources

LG mini-split 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

Soft lockoutShown as: Outdoor LED01 (red) blinks 3 times, LED02 (green) blinks 9 times

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.

Source

LG mini-split code CH40: Current transformer

Hard lockoutShown as: Outdoor LED01 (red) blinks 4 times, LED02 (green) does not blink

Current transformer (CT) sensor error - the current-sensing circuit on the outdoor board is open or shorted.

Manual wording: “CT Sensor Error; Thermistor is disconnected or has shorted out”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. PCB current-sensing circuit part burned out

When to call a technician

The service manual states that because CH40 is caused by burned-out components on the outdoor PCB, the board is replaced without separate inspection. Technician only.

Sources

LG mini-split code CH41: Inverter compressor discharge pipe

Soft lockoutShown as: Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 1 time

Inverter compressor discharge pipe (D-pipe) sensor is disconnected or shorted out. The thermistor that watches compressor discharge temperature is not reporting.

Manual wording: “Inverter compressor discharge pipe (D-Pipe) sensor is disconnected or has shorted out”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Sensor mis-wiring or short at the connector
  2. Moisture penetration into the sensor or bad canning sheath on the sensor wire

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 discharge sensor sits on hot compressor piping inside the outdoor unit's electrical area. Technician only.

Sources

LG mini-split code CH42: Low pressure sensor open or short

Soft lockoutShown as: Outdoor LED1 blinks 4 times, LED2 blinks 2 times (2-LED type)

Low pressure sensor open or short. The suction-side pressure transducer is not reporting a valid signal.

Manual wording: “Low pressure Sensor open/short”

Documented for: LG single-zone room air conditioner / mini-split outdoor units fitted with pressure sensors

Likely causes, most common first

  1. Bad wiring of the pressure sensor
  2. Bad pressure sensor

What you can safely check yourself

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

When to call a technician

Pressure transducers are mounted on the refrigerant circuit. Replacement is technician work.

Source

LG mini-split code CH43: High pressure sensor is disconnected or shorted out

Soft lockoutShown as: Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 3 times

High pressure sensor is disconnected or shorted out. The discharge-side pressure transducer is not reporting a valid signal.

Manual wording: “High pressure sensor is disconnected or has shorted out”

Documented for: All LG residential mini-split outdoor units fitted with pressure sensors

Likely causes, most common first

  1. Bad wiring of the pressure sensor
  2. Bad pressure sensor

What you can safely check yourself

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

When to call a technician

Pressure transducers are mounted on the refrigerant circuit. Replacement is technician work.

Sources

LG mini-split code CH44: Outdoor air

Soft lockoutShown as: Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 4 times

Outdoor air (inlet) temperature sensor is disconnected or shorted out. The outdoor unit cannot read ambient temperature, so it cannot run its defrost and capacity logic.

Manual wording: “Outdoor air sensor is disconnected or has shorted out”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Sensor mis-wiring or short at the connector
  2. Moisture penetration into the sensor or bad canning sheath on the sensor wire

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 ambient sensor is inside the outdoor unit's cabinet. Measuring and replacing it is technician work.

Sources

LG mini-split code CH45: Mid-pipe thermistor of the outdoor unit condenser coil is disconnected or shorted out

Soft lockoutShown as: Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 5 times

Mid-pipe thermistor of the outdoor unit condenser coil is disconnected or shorted out. This is the sensor the unit uses to judge coil temperature for defrost.

Manual wording: “Mid-pipe thermistor of outdoor unit condenser is disconnected or has shorted out”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Sensor mis-wiring or short at the connector
  2. Moisture penetration into the sensor or bad canning sheath on the sensor wire

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 coil sensor is clamped to refrigerant piping inside the outdoor cabinet. Technician only.

Sources

LG mini-split code CH46: Outdoor unit suction pipe thermistor is disconnected or shorted out

Soft lockoutShown as: Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 6 times

Outdoor unit suction pipe thermistor is disconnected or shorted out. The sensor on the compressor suction line is not reporting.

Manual wording: “Outdoor unit suction piping thermistor is disconnected or has shorted out”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Sensor mis-wiring or short at the connector
  2. Moisture penetration into the sensor or bad canning sheath on the sensor wire

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 suction sensor is on refrigerant piping inside the outdoor cabinet. Technician only.

Sources

LG mini-split code CH48: Outdoor unit condenser coil outlet

Soft lockoutShown as: Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 8 times

Outdoor unit condenser coil outlet (liquid line) thermistor is disconnected or shorted out.

Manual wording: “Outlet piping (liquid) of condenser is disconnected or has shorted out”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Sensor mis-wiring or short at the connector
  2. Moisture penetration into the sensor or bad canning sheath on the sensor wire

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 liquid line sensor is on refrigerant piping inside the outdoor cabinet. Technician only.

Sources

LG mini-split code CH51: Over capacity / combination ratio out of range

Hard lockoutShown as: Outdoor LED01 (red) blinks 5 times, LED02 (green) blinks 1 time

Over capacity / combination ratio out of range. The total capacity of the connected indoor units is under 50% or over 130% of the outdoor unit's capacity. On multi-zone systems this is an installation or wiring mistake, not a component failure.

Manual wording: “Combination ratio (capacity) is out of range; Total nominal indoor unit capacity is <50% or >130% of the outdoor unit capacity”

Documented for: LG Multi F / Multi F MAX multi-zone systems, and single-zone systems with a mismatched indoor/outdoor pair

Likely causes, most common first

  1. Mis-wiring between indoor and outdoor units
  2. Wrong wiring or piping connection during installation of several similar models at the same site (zone A's pipe run connected to zone B's wiring)
  3. Indoor units connected that add up to too little or too much capacity for the outdoor unit

When to call a technician

CH51 means the system was put together in a combination LG does not allow, or the zone wiring and piping were crossed at install. The installer needs to come back and verify each indoor unit's wiring matches its piping.

Sources

LG mini-split code CH53: Communication failure from the outdoor unit to the indoor unit

Soft lockoutShown as: Outdoor LED01 (red) blinks 5 times, LED02 (green) blinks 3 times

Communication failure from the outdoor unit to the indoor unit(s). Same fault family as CH05, but reported from the outdoor side - the outdoor board is not hearing the indoor unit.

Manual wording: “Communication failure between outdoor unit and indoor unit(s)”

Documented for: All LG residential mini-splits, single-zone and multi-zone

Likely causes, most common first

  1. No power on the indoor unit
  2. Indoor/outdoor unit power connection error, or the communication line not installed
  3. Improper connection at the terminal block for the communication wire
  4. Improper wiring of the communication L-N wire between indoor and outdoor units
  5. Communication error caused by external electrical noise
  6. Indoor/outdoor communication circuit parts burned, or no power due to a burned indoor or outdoor PCB

What you can safely check yourself

  • Check the breakers for BOTH the indoor and outdoor unit are on and not tripped
  • Check the outdoor disconnect switch next to the condenser is switched on
  • Turn the system off at the breaker for three minutes, then back on

When to call a technician

If power is on at both units and CH53 stays, the interconnecting wiring or a control board is at fault. That is technician work.

Sources

LG mini-split code CH54: Open phase / reverse phase error - the outdoor unit's incoming power is missing a leg or wired in the wrong order

Hard lockoutShown as: Outdoor LED01 (red) blinks 5 times, LED02 (green) blinks 4 times

Open phase / reverse phase error - the outdoor unit's incoming power is missing a leg or wired in the wrong order. LG's consumer page notes this usually shows up after a power outage or electrical work.

Manual wording: “Outdoor unit is not wired properly (ex: reversed phase)”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Outdoor unit is not wired properly (for example, reversed phase)
  2. A power leg lost or reconnected in the wrong order after an outage or electrical work

What you can safely check yourself

  • Check the breaker feeding the outdoor unit is fully on and not partially tripped
  • Check the outdoor disconnect switch is fully seated and on

When to call a technician

If this appeared after a power outage, a panel change, or any electrical work, an electrician or HVAC technician needs to confirm the incoming power was reconnected correctly. Do not open the outdoor unit's electrical box.

Sources

LG mini-split code CH60: Outdoor unit PCB EEPROM check sum error

Hard lockoutShown as: Outdoor LED01 (red) blinks 6 times, LED02 (green) does not blink

Outdoor unit PCB EEPROM check sum error. The memory chip on the outdoor control board that stores the unit's identity and factory parameters failed its integrity check.

Manual wording: “Outdoor unit printed circuit board (PCB) EEPROM check sum error”

Documented for: All LG residential mini-split 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

A failed EEPROM checksum means the outdoor control board cannot trust its own configuration. A technician has to replace the board.

Sources

LG mini-split code CH61: Outdoor unit condenser coil pipe temperature is too high

Soft lockoutShown as: Outdoor LED01 (red) blinks 6 times, LED02 (green) blinks 1 time

Outdoor unit condenser coil pipe temperature is too high. In cooling this means the outdoor unit is overheating; in heating it means the indoor coil is overheating. In both cases the system cannot get rid of the heat it is making.

Manual wording: “Condenser coil thermistor temperature is 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
  2. Heat exchanger (coil) contaminated with dirt, lint, cottonwood, or grass clippings
  3. Poor condenser pipe sensor assembly or burned sensor
  4. EEV connector displaced or poor EEV assembly
  5. Refrigerant overcharged

What you can safely check yourself

  • Clear leaves, grass clippings, cottonwood, snow, or debris away from the outdoor coil and fan
  • Remove anything stacked against or on top of the outdoor unit, and check there is clear space all around it
  • Check and clean the indoor air filters
  • Make sure the indoor supply and return grilles are open and unblocked
  • Let the unit cool, then turn it off at the breaker for three minutes and back on

When to call a technician

If airflow is clear on both units and CH61 returns, the coil needs a proper cleaning or the charge and expansion valve need checking. Call a technician.

Sources

LG mini-split code CH62: Outdoor unit inverter compressor PCB heat sink temperature is too high

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

Outdoor unit inverter compressor PCB heat sink temperature is too high. The aluminium heat sink that cools the inverter power module is overheating, usually because the outdoor unit is in a hot, cramped spot or its airflow is blocked.

Manual wording: “Outdoor unit inverter compressor PCB heat sink temperature is too high”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Improper installation environment (outdoor unit in a tight, unventilated location)
  2. Overload operation - outdoor fan restricted, screened, or blocked
  3. Poor PCB heat sink assembly (heat sink not making good contact)
  4. Poor PCB temperature sensing circuit parts

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 and give it clear space on all sides
  • Check nothing is blowing hot exhaust (dryer vent, another condenser) into the outdoor unit
  • Let the unit cool, then turn it off at the breaker for three minutes and back on

When to call a technician

If the outdoor unit has clear airflow and CH62 returns, the heat sink mounting or its sensor is at fault and needs a technician. If the unit is genuinely in too tight a space, it may need relocating.

Sources

LG mini-split code CH63: Condenser coil pipe thermistor temperature is too low

Soft lockoutShown as: Outdoor LED1 blinks 6 times, LED2 blinks 3 times

Condenser coil pipe thermistor temperature is too low. In heating mode this typically means the outdoor coil is icing or the system is not absorbing heat.

Manual wording: “Condenser coil pipe thermistor temperature is too low.”

Documented for: LS091HSV / LS121HSV systems (LSU091HSV / LSU121HSV outdoor units)

What you can safely check yourself

  • Clear snow and ice away from around, under, and on top of the outdoor unit
  • Make sure the outdoor unit is not sitting in a drift or a spot where roof runoff pours onto it
  • Check and clean the indoor air filters

When to call a technician

If the outdoor unit is clear of snow and CH63 returns, the defrost system, charge, or the coil sensor needs a technician. Do not chip ice off the coil - the fins and refrigerant tubing damage easily.

Source

LG mini-split code CH65: Heat sink thermistor is disconnected or shorted out

Soft lockoutShown as: Outdoor LED01 (red) blinks 6 times, LED02 (green) blinks 5 times

Heat sink thermistor is disconnected or shorted out. The sensor that monitors the inverter power module's heat sink is not reporting.

Manual wording: “Heat sink thermistor is disconnected or has shorted out”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Sensor mis-wiring or short at the connector
  2. Moisture penetration into the sensor or bad canning sheath on the sensor wire

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 heat sink sensor sits on the live inverter board assembly. Technician only.

Sources

LG mini-split code CH67: Outdoor BLDC fan motor lock error

Hard lockoutShown as: Outdoor LED01 (red) blinks 6 times, LED02 (green) blinks 7 times

Outdoor BLDC fan motor lock error. The outdoor fan is not turning when the board tells it to - usually something is physically jamming it (ice, leaves, a stick), or the motor or its connector has failed.

Manual wording: “Outdoor unit brushless direct current (BLDC) fan motor lock error”

Documented for: All LG residential mini-split outdoor units with BLDC fan motors

Likely causes, most common first

  1. Fan locked by physical force (foreign object stuck in the motor or blade)
  2. Poor connection of the motor connector
  3. Motor failure
  4. PCB failure

What you can safely check yourself

  • Turn the outdoor unit off at the breaker first, then look through the grille for leaves, sticks, ice, or debris jamming the fan blade
  • Clear snow and ice from around, under, and on top of the outdoor unit
  • Once the obstruction is removed and the breaker is back on, try the system again

When to call a technician

If nothing is jamming the fan and CH67 returns, the fan motor or the outdoor control board has failed. Never reach into the outdoor fan with power on.

Sources

LG mini-split code CH72: Four-way

Soft lockoutShown as: Outdoor LED1 blinks 7 times, LED2 blinks 2 times (2-LED type)

Four-way (reversing) valve switching failure. The valve that flips the system between heating and cooling did not change over when commanded, so the unit cannot switch modes.

Manual wording: “Switching for 4 way valve is failed”

Documented for: LG single-zone room air conditioner / mini-split heat pump outdoor units

Likely causes, most common first

  1. Indoor or outdoor pipe sensor short or open
  2. Disconnection of the 4-way valve connector
  3. 4-way valve coil open or short
  4. Burned part inside the PCB (4-way valve output)

What you can safely check yourself

  • Turn the system off at the breaker for three minutes and back on, then try the mode change again

When to call a technician

The reversing valve and its coil are on the refrigerant circuit inside the outdoor unit. A technician has to measure the coil resistance and the board's output before deciding what to replace.

Source

LG mini-split code CH73: PSC / PFC overcurrent error detected in software - the outdoor unit's power factor correction stage saw a current peak beyond its limit

Soft lockoutShown as: Outdoor LED01 (red) blinks 7 times, LED02 (green) blinks 3 times

PSC / PFC overcurrent error detected in software - the outdoor unit's power factor correction stage saw a current peak beyond its limit. Same protection as CH27 but caught by the firmware rather than the hardware trip.

Manual wording: “PSC / PFC overcurrent error (SW)”

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 stage and reactor are inside the live inverter section of the outdoor unit. Call a technician.

Sources

LG mini-split code CH93: Indoor / outdoor unit communication error

Soft lockout

Indoor / outdoor unit communication error. LG's consumer support page describes CH93 as a communication problem between the indoor and outdoor units; the service manual handles it with the same troubleshooting flow as CH05 and CH53.

Manual wording: “Indoor / outdoor unit communication error”

Documented for: LG single-zone room air conditioner / mini-split systems

Likely causes, most common first

  1. No power on the indoor unit
  2. Indoor/outdoor unit power connection error, or the communication line not installed
  3. Improper connection at the terminal block for the communication wire
  4. Improper wiring of the communication L-N wire between indoor and outdoor units
  5. Communication error caused by external electrical noise
  6. Indoor/outdoor communication circuit parts burned, or no power due to a burned indoor or outdoor PCB

What you can safely check yourself

  • Check the breakers for BOTH the indoor and outdoor unit are on and not tripped
  • Check the outdoor disconnect switch next to the condenser is switched on
  • Turn the system off at the breaker for three minutes, then back on

When to call a technician

If power is confirmed on at both units and CH93 stays, the interconnecting communication wiring or a control board needs a technician.

Sources

How old is this LG?

Age changes what a fault code means for you. The same failure is a routine repair on a six-year-old unit and the end of the line on a twenty-year-old one. Your LG serial number has the build date in it.

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Manuals used for this page