LG air conditioners report faults as CH codes — CH05 is a communication fault between the indoor and outdoor units, CH38 means the system is low on refrigerant, and CH04 means condensate is not draining. Only a handful of LG codes point at something a homeowner can fix (a blocked drain, a dirty filter, a tripped breaker). Anything involving refrigerant, the compressor or the outdoor control board needs a licensed technician.
How LG error codes work
When an LG system detects a fault it stops the affected function and shows a code on the indoor unit display, the wired controller, or as a blink pattern on the indoor unit’s LEDs. On most residential LG units the code appears as CH followed by two digits. Some model ranges show the same fault in a shorter form — LG’s own documentation pairs CH05 with E0 and CH53, and CH38 with F4, because they describe the same underlying condition on different hardware generations.
An important thing to understand: the code tells you which protection tripped, not which part failed. CH38 says pressures look like a low-charge system — it does not tell you where the leak is. Treat the code as the start of a diagnosis, not the answer.
Common LG error codes and what they mean
| Code | What LG says it means | What to do |
|---|---|---|
| CH04 | Condensate formed in the indoor unit is not draining | Check the drain line and pump — often clearable |
| CH05 / E0 / CH53 | Communication error between indoor and outdoor units | Check power to the outdoor unit, then call a technician |
| CH07 | Operating mode conflict between units on one system | Set all indoor units to the same mode (heat or cool) |
| CH10 / E6 | Indoor unit fan problem | Check for anything blocking the blower; otherwise technician |
| CH34 / CH61 / P4–P8 | Overheating — outdoor unit in cooling, indoor unit in heating | Clear airflow blockages, clean filters and the outdoor coil |
| CH38 / F4 | Air conditioner is low on refrigerant | Licensed technician only — this is a leak, not a top-up |
| CH54 | Reverse phase detected after a power supply problem | Electrician — do not attempt |
| CH66 | Communication or piping connection issue between units | Technician — usually an installation fault |
| CH67 / EF | Outdoor unit fan problem | Check for debris in the fan; otherwise technician |
| CH90 / CH91 | Test run phase error or piping problem | Technician — commissioning fault |
| CH93 | Communication problem between indoor and outdoor units | Technician |
| CH237 / CH238 | Outdoor unit power disconnected, or breaker issue | Check the outdoor disconnect and breaker |
What you can safely check yourself
Switch the system off at the thermostat or remote and turn off the breaker that feeds the outdoor unit. Never remove the electrical cover from an outdoor condenser or an indoor fan coil — the capacitors inside hold a charge after the power is off. If a code points at wiring, a control board or refrigerant, stop here and book a technician.
- Write the code down before you reset anything
Power cycling clears the display, and with it the only clue you have. Photograph the display first. If the code returns, note how long it took — a fault that reappears within minutes behaves very differently from one that comes back after a day.
- Clear the condensate drain for CH04
CH04 is the most homeowner-fixable LG code. Find the drain line leaving the indoor unit, check it is not kinked or running uphill, and clear the trap of slime and grit. On wall-mounted units the small condensate pump can also stick. If water is already dripping from the indoor unit, see our guide on AC leaking water.
- Restore airflow for CH34, CH61 and the P-series overheat codes
These codes mean a coil could not shed heat. Wash or replace the indoor filters, make sure furniture and curtains are not blocking the indoor unit, and clear leaves, grass and fencing from around the outdoor unit — it needs clear air on all sides and above.
- Check outdoor unit power for CH237, CH238 and CH05
Look at the breaker feeding the outdoor unit and at the outdoor disconnect switch beside it. A tripped breaker or a disconnect left open after service produces exactly the “no communication” symptom. Reset a tripped breaker once. If it trips again, stop — that is a fault, not a nuisance trip.
- Match the operating mode for CH07
On a multi-split, all indoor units share one outdoor compressor and therefore one mode. If one room asks for heat while another asks for cooling, the system flags a mode conflict. Set every head to the same mode and the code clears.
- Reset and watch
Turn the breaker off for two minutes, then back on, and run the system while you watch it. Note whether the outdoor fan spins, whether the compressor starts, and how long the unit runs before the code returns. That detail saves a technician a diagnostic hour.
Why CH38 is not a DIY repair
CH38 and F4 mean LG’s control board has decided the system is short of refrigerant. A sealed air conditioning system does not consume refrigerant — if the charge is low, it leaked out. Adding refrigerant without finding and repairing the leak wastes money, and in the US it is illegal to knowingly vent refrigerant or to buy most refrigerants without EPA Section 608 certification. A technician will pressure-test the system, locate the leak, repair it, evacuate the lines and weigh in a measured charge. Cans of “AC recharge” sold for cars are not appropriate for a home split system.
Refrigerant lines run at high pressure and can cause frostbite and eye injury. Refrigerant service is restricted to certified technicians. Anything involving the outdoor unit’s control board, the compressor, or the incoming power supply — including the CH54 reverse phase code — belongs to a licensed electrician or HVAC technician, not to a homeowner with a multimeter.
When to call a professional
Call a technician if the code involves refrigerant (CH38, F4), the compressor or inverter, the outdoor control board, or any communication fault that survives a power cycle and a breaker check. Call an electrician for CH54 and for any breaker that trips repeatedly. And call sooner rather than later for CH38 — running a system on a low charge lets the compressor run hot and poorly lubricated, which turns a leak repair into a compressor replacement.
