This site is not affiliated with LG; this is an independent explanation.
The LG AC CH 05 error code tells you the indoor unit has lost its signal link with the outdoor unit. On most LG split and inverter models the display shows CH05 (written CH 05 in many searches), the cooling stops, and the outdoor fan and compressor stay silent.
The two boxes of a split AC trade short messages all the time. When the replies stop, the indoor board gives up after a short wait and shows this code. The cause can be as small as a switched off outdoor isolator or as big as a damaged board, so the order of checks below matters.
Common causes
1Outdoor unit has no power
How to tellIndoor fan runs but nothing happens outside; isolator or MCB is off
What fixes itSwitch on the outdoor isolator and MCB, then restart
2Power cut or voltage dip
How to tellCode appears just after the supply returns
What fixes itWait ten minutes with the main switch off, then restart
3Loose or damaged connecting cable
How to tellCode comes and goes with wind, rain or vibration; cable looks chewed or sun-cracked
What fixes itTechnician checks the cable and terminals
4Rodent or insect damage
How to tellDroppings or chewed insulation near the pipe entry
What fixes itTechnician repairs the wiring; do not tape it yourself
5Indoor or outdoor board fault
How to tellPower and cable both checked, code stays
What fixes itAuthorised service tests the boards
6Heavy electrical noise or poor earthing
How to tellCode appears with certain appliances starting nearby
What fixes itElectrician checks earthing and supply quality
How to fix it, step by step
Read the display and write the code down
Confirm it says CH05 and not CH10 or another CH code. If you see CH10, open LG AC CH10 error, because the story differs.
Check the outdoor isolator and the AC's MCB
Many homes have a small switch box near the outdoor unit and a breaker in the main panel. Look at both and switch them on if they are down. A forgotten switch after maintenance is one of the most common reasons for CH05.
Glance at the outdoor box from somewhere safe
Watch whether the fan spins within a minute of the AC starting. If it is still and the isolator is on, the outdoor part may not be receiving power or a command. Do not open the unit.
Do a full power reset
Drop the MCB, count out ten minutes, then raise it and begin cooling again. This lets the boards drain and restart their link check. If the code does not come back for a few days, it was a glitch from a supply dip.
Check for obvious outside damage
Without touching wires, look where the pipe enters the wall. Chewed insulation, a pipe sleeve pulled out of place or a wet junction can be reasons. Report it to the technician instead of repairing it.
Try a different time of day
If CH05 comes at the peak evening load and not in the morning, tell the technician. It can suggest a supply problem or a loose joint that grows hot.
Call LG authorised service
Read out the model name on the label, the code and what you noticed. If the AC is under cover, the authorised route keeps your warranty intact.
LG AC CH 05 error code meaning on an inverter AC
CH stands for a check code in the LG display family, and the number tells the board which check failed. A technician will tell you that CH05 points to the communication link on most models, and the same reading is common for LG inverter splits. Yet the tables are not identical for every year, so read your manual or quote the model to the brand's helpline.
After a long power cut the lights come back, you press the remote and the indoor fan blows air that is not cold. Two minutes later the screen shows CH05. The outdoor isolator was knocked down during the cut. Raising it and doing a ten minute reset restores cooling.
CH05 compared with other CH codes
| Display | Usual area on most models | Page |
|---|---|---|
| CH05 | Indoor and outdoor communication | This page |
| CH10 | A different check; read its own page | LG AC CH10 |
| Other CH or E codes | Varies by series | LG AC error codes |
A table like this is a starting point and not a repair order.
What not to do about CH05
Do not open the outdoor unit, pull or join the connecting wire, press buttons on the board, or bypass the link with a jumper. The cable can carry a live supply on some models, and the boards are sensitive. Each of these shortcuts invites an electric shock, a fire or a costly board failure, and any of them can cancel your warranty.
Only a trained technician should handle gas, wiring and boards. Burning smell, sparks or repeated MCB tripping means switch the AC off and call service the same day.
How long it takes and what changes the cost
Putting an isolator back on takes a minute, and tightening a loose joint is a short visit. A chewed cable run, rodent repair or board change takes more time and money, depending on which board it is, the warranty and the access to the outdoor box. Get the part named in a written quote before you agree.
Keeping the link healthy
Seal the pipe hole against rodents, keep the outdoor unit shaded from heavy rain splash and fit a suitable voltage protector if your supply swings. When you plan a servicing visit, ask the technician to check the cable terminals. The wider list of brand codes is on the AC error codes page, and a unit that cools badly without any code is covered by the cooling troubleshooting page.
Frequently asked questions
What does CH05 mean on an LG AC?
On most LG split models it means the indoor unit has lost communication with the outdoor unit. Your model's own table in the manual is the final word.
What is the lg inverter ac ch 05 error code?
It is the same communication alert on an inverter split. The outdoor unit may be off, the cable may be loose or damaged, or a board may be at fault.
Can I fix CH05 by pressing reset on the remote?
No. A remote does not clear a real link fault. Do a full MCB power reset once, and if the code returns call service.
Is CH05 dangerous?
The code is a protection message, so the unit stops. The danger is in opening the units or touching cables, which you should not do. Call a technician if there is a burning smell.
Why does CH05 come after a power cut?
A power cut can drop the outdoor isolator or MCB, or the boards can lose their link when the supply returns with a spike. Switch on all breakers and reset once.
What is the difference between CH05 and CH10 on LG?
They are separate checks and have different pages. Read the one that matches your display and do not use one code's advice for the other.