- HVAC
- Air conditioner
CH93
LG CH93 on an air conditioner: indoor and outdoor link fault
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
CH93 means the indoor and outdoor units are not communicating reliably. On LG units built after 2021 it also shows when the outdoor unit gets no power: check its plug and the breaker, then reset once, waiting about 5 minutes before restoring power.
Safety first
Stop and check this first
- Do not take the air conditioner apart or swap internal parts: LG warns of fire, electric shock, serious injury or death. If CH93 returns after the reset, leave the unit off and request service so the damage does not get worse.
- If the air conditioner breaker will not stay on, LG asks you not to reset it over and over: leave the unit without power and request an inspection.
Safe checks you can perform
- Place when CH93 appeared
- Outdoor unit's own plug
- Air conditioner circuit breaker
- Single reset with a 5 minute wait
- Communication line and supply between units
Leave these tasks to a qualified professional
- Do not attempt this professional task: Confirm the power configuration
- Do not attempt this professional task: Repeat the test run
- Do not attempt this professional task: Measure voltage and signal between units
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Confirm the power configuration
What they doOn units from after 2021, the technician confirms that each unit has its own wall socket and that the wiring matches LG's revised communication layout.
They must show youthe socket feeding each unit and the model diagram compared with the installation.
In writinghow each unit ends up powered and any connection changed.
Repeat the test run
What they doAfter fixing the fault, the technician runs the full test in cooling and, where the unit allows, in heating, watching that CH93 does not come back.
They must show youthe unit running in each mode with the display clear of CH93.
In writingthe modes tested, how long the test lasted and the date.
Measure voltage and signal between units
What they doThe technician measures the voltage reaching the outdoor unit and across the communication terminals, and checks the link cable along its full length.
They must show youthe voltage read at each terminal and the condition of the link cable.
In writingthe code CH93, the readings, the repair made or the part replaced with its reason, and the date.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Place when CH93 appeared
- Who:
- you.
- How:
- make sure the indoor display shows CH followed by 93, and recall whether the unit had just been installed, moved, or had been running without trouble for some time.
- Result that matters:
- telling a start-up CH93 apart from one that arose with the unit already in use.
- If it showed in the first test after installation or a move:
- check the outdoor plug and breaker and, if it stays, contact the installer.
- If it showed during everyday use:
- continue with the power checks and the reset.
- Evidence to keep:
- a photo of CH93 on the display, the day of the installation or move and who did it.
Evidence: LG Air Conditioner - Guide to Error Codes
Outdoor unit's own plug
- Who:
- you, without opening any cover.
- How:
- if your model is from after 2021 and the outdoor unit has its own cord, make sure its plug sits firmly in a wall socket, not in a power strip or an extension lead.
- Result that matters:
- that the outdoor unit gets power through its own plug, as LG requires on these models.
- If it was loose or in a power strip:
- plug it firmly into a wall socket and switch the unit back on.
- If it was already plugged firmly into the wall:
- move on to the air conditioner breaker.
- Evidence to keep:
- how the outdoor plug was connected and whether CH93 cleared once corrected.
Evidence: LG Air Conditioner - Guide to Error Codes
Air conditioner circuit breaker
- Who:
- you.
- How:
- open the consumer unit and find the breaker for the air conditioner. If it is off, switch it on once. LG asks you not to keep trying if it will not stay on.
- Result that matters:
- that the air conditioner breaker stays switched on.
- If it switches on and holds:
- start the unit with the remote and watch whether CH93 returns.
- If it will not switch on or trips at once:
- do not force it again, request service.
- Evidence to keep:
- the position the breaker was in and whether it tripped again when switched on.
Evidence: LG Air Conditioner - Guide to Error Codes
Single reset with a 5 minute wait
- Who:
- you.
- How:
- with the remote set to off, unplug the unit or switch off its breaker, let about 5 minutes pass as LG states for CH93 and restore power. Do this only once.
- Result that matters:
- finding out whether the communication drop was passing.
- If the unit starts without CH93:
- use it normally and note the date in case it recurs.
- If CH93 comes back:
- LG says to request service, stop resetting.
- Evidence to keep:
- the time of the reset and how many minutes CH93 took to return, if it did.
Evidence: LG Air Conditioner - Guide to Error Codes
Communication line and supply between units
- Who:
- certified HVAC technician (F-gas certified in the EU or local equivalent), for the CH93 wiring.
- How:
- with power isolated, inspect the cable joining the two units, its terminals and the outdoor unit supply, following the model's wiring diagram.
- Result that matters:
- finding the point where the communication behind CH93 is lost.
- If there is a loose terminal, a cut cable or a wrong connection:
- it is repaired and the test run is repeated.
- If the connections are sound:
- the technician moves on to voltage readings and the model's service mode.
- Evidence to keep:
- a report listing the terminals checked, the voltages measured and photos of the wiring.
The terminals and the outdoor unit board run at mains voltage: certified technician only, never open the covers yourself.
Evidence: LG Air Conditioner - Guide to Error Codes
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- HVAC
- Brand
- LG
- Product type
- Air conditioner
Known code variants
- CH93
- error 93 aire LG
- LG AC error 93
- LG CH 93
- LG CH93
What it means
In LG's error code guide for split and window air conditioners (Help Library), CH93 indicates a communication problem between the indoor and outdoor units. It typically shows during the test run after installing or relocating the unit. On models made from 2021 each unit has its own power cord, so CH93 also appears when the outdoor unit has no power. LG notes that the guide covers all its models and yours may differ. Seeing CH93 on the display is not enough to call any part of the unit faulty.
Warnings and stop conditions
- Higheditorial warning
Do not take the air conditioner apart or swap internal parts: LG warns of fire, electric shock, serious injury or death. If CH93 returns after the reset, leave the unit off and request service so the damage does not get worse.
Evidence: How to Troubleshoot Error Codes CH01, CH02, CH06 on Your LG Air Conditioner
- Mediumsource verified
If the air conditioner breaker will not stay on, LG asks you not to reset it over and over: leave the unit without power and request an inspection.
Evidence: LG Air Conditioner - Guide to Error Codes
Symptoms and causes
Probable causes · in order
- Outdoor unit without powerCommon
On LG models from after 2021, where each unit has its own power cord, CH93 appears if the outdoor unit is unplugged or its circuit breaker is off.
Evidence: LG Air Conditioner - Guide to Error Codes
- Unstable communication at start-upCommon
LG says CH93 typically shows during the test run, right after installing or moving the unit, while communication between the units is not yet stable.
Evidence: LG Air Conditioner - Guide to Error Codes
- Power strip shared with other appliancesPossible
LG advises against plugging the unit into a power strip: sharing it with other appliances may exceed its capacity and leave the unit short of the supply it needs.
Evidence: LG Air Conditioner - Guide to Error Codes
- Unstable mains supplyPossible
If CH93 shows during normal use, LG puts it down to a passing fault from unstable power or other electrical factors, which a reset clears.
Evidence: LG Air Conditioner - Guide to Error Codes
Virtual technician
Does CH93 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
LG Air Conditioner - Guide to Error Codes
LG Electronics · 2026 · official_doc
- 2
How to Troubleshoot Error Codes CH01, CH02, CH06 on Your LG Air Conditioner
LG Electronics · 2026 · official_doc
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