How To Troubleshoot LG Mini Split AC?

An LG mini split AC has an LED monitor that will display an error code whenever something in the system goes wrong. To troubleshoot the unit, you would have to:

1. Locate the LED monitor.

Write down the error code or count the flashes.

Find the error code in the list provided and follow the instructions.

Do bear in mind that some issues are easy to fix while others would require a visit from an HVAC technician. Below you will find some helpful recommendations.

How to Troubleshoot LG Mini Split AC – Error Codes List?

Some error codes might not get displayed on the indoor unit. So, the best way to check for any errors is by inspecting the LED monitor on the outdoor unit.


CH00 typically indicates an electrical problem.

Make sure that there are no power issues in your building. If everything is alright, unplug the mini split for 5 minutes and plug it back in.

If that did not fix the issue, then call an expert as trying to deal with electricity-related issues on your own is not recommended.

Read: Why Is AC Mini Split Making Noise When Off? How To Troubleshoot It?


There is an issue with the unit’s automatic shut-off feature. That might be because there is an electrical problem affecting the temperature sensor.

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Unfortunately, you won’t be able to take care of the issue yourself. So, make sure to call a professional.


The mini split has detected a low refrigerant level. As the substance does not get used during operation, the chances are high that there is a leak somewhere in the system.

If you have noticed that the AC is no longer cooling properly and the monitor is showing such an error code, then stop using the unit and schedule a refrigerant refill. If the mini-split continues to operate, it might lead to refrigerant poisoning.

CH05/5 flashes

This error code indicates that the indoor and outdoor units are unable to communicate. You might have to deal with such an issue if you have a blown fuse, a tripped breaker, or faulty or loose wiring.

You can reset the breaker and replace a blown fuse if you have the necessary skills. If you feel comfortable doing that, you can also inspect the wiring and ensure that all the connections are secure.


If you have a few indoor units, the CH07 error code will pop up, if one of the units is set to ‘cool’ while the other one is in ‘heat’ mode.

All you would have to do to clear the code is set all indoor units to heating or cooling. You can also unplug the units for 5 minutes and then switch them back on if the code does not clear automatically.

Read: Why Mini Split Fan Runs Continuously?

CH10/1 flash

The fan motor in the indoor unit is defective.

You might want to invite an expert over for this one as the troubleshooting involves measuring the fan motor phase resistance and checking the indoor unit’s PCB.

If the fan motor has gone bad, the professional would have to replace it.


There is a DC link error (high/low DC voltage).

The first thing that you should do is check the power supply to the unit. If you know how to use a multimeter, you can check the voltage, as well as the compressor wiring.

There might be a problem either with the compressor, or the PCB board.

Read: Can A Mini Split Cool A Whole House?


The compressor was not connected properly and the unit will not run until you fix the issue. This might be a job for an HVAC expert.


There is an inverter compressor overcurrent error which basically means that there is something wrong with the DC link.

You can check the main power supply, the refrigerant flow, and the compressor wiring, or leave the job to a professional.


This code indicates that the mini-split is overheating.

A clogged air filter and dirty coils can make the unit overwork and, as a result, overheat. So, make sure to check those.

By the way, ideally, you wouldn’t want to install the mini split in a place where it’ll constantly be under direct sunlight. Exposure to sun rays can lead to an increase in pressure in the mini-split’s sealed system.

Read: How To Choose The Right Size Mini Split?


The low-pressure sensor is faulty. The main job of this element is to shut the mini-split down whenever the pressure in the system is too low. This helps prevent compressor damage.

The error can be caused by quite a few different things. You can check the outdoor unit and make sure that it’s clean and that there’s nothing blocking it.

A refrigerant leak, an improperly connected or faulty sensor, and a bad control board might also be to blame. But all these issues should be taken care of by a professional.


CH38 means that there is either unstable power or a refrigerant leak. Make sure that the unit is receiving electricity and then unplug the mini-split for 5 minutes.

If that did not clear the code, there might be a refrigerant leak.

Read: Do I Need A Mini Split In Every Room?


The outdoor unit’s fan is malfunctioning.

An HVAC expert would have to check the installation of the fan. The professional would also inspect the connection of the fan motor harness and measure the resistance of fan phases.

If everything is fine, then the problem might be with the control board.


The drain pan is full. This can happen if the drain pipe is clogged, the coil is frozen, or if the unit hasn’t been installed correctly.

You might also want to consider increasing the unit’s fan speed as this can improve water drainage.

Do bear in mind that a full drain pan can become an issue on extra humid days. If that’s the case, you would want to keep the doors and windows closed and, perhaps, run a dehumidifier.


E4 is not an error code. It simply appears whenever the mini-split goes into defrost mode – an automatic process that forces warm air to go over the coils to defrost them.

It is completely normal for the unit to go into defrost mode (but not more often than once every 35 minutes on extra cold days).

In the majority of cases, all you would have to do is wait for 5-15 minutes for the unit to complete the cycle and return back to normal operation.


Some LG air conditioner models have a collection tank where the condensing water gets drained. If the water is unable to drain from the tank, an error code will appear.

Remove the drain cap from the tank and allow all the water to flow out. After that, reinstall the cap. If the code did not get automatically cleared, then reset the unit.


The codes that begin with an ‘F’ are not error codes. They simply indicate that the mini split is operating in fan mode.

Final Thoughts

The good news is that, in some cases, you will be able to troubleshoot your LG mini split AC yourself. For example, you can check the breaker, change the filter, and clean the unit, if the instructions suggest doing that.

Sometimes, unplugging the unit for 5 minutes would be enough to clear the error code. In all the other cases, make sure to call an HVAC expert.