LG's window, through-the-wall and portable air conditioners do not use the two-letter codes of its laundry products or the F codes of its cooking products. They report faults as CH followed by two digits, and LG's air conditioner code guide states simply that the letters CH precede every code on the list. The same CH vocabulary runs through LG's ductless mini-split systems, which is why an owner searching a code often lands on an explanation written for a different kind of unit. The digits, not the letters, carry the meaning.
The Three Families
Read across LG's list and the codes sort themselves into groups. The low numbers describe sensors: CH01 is the thermistor that reads room air at the indoor side, CH02 the thermistor on the indoor coil piping. A middle group describes communication and motors: CH05 is the indoor unit failing to talk to the outdoor unit on a split system, and CH10 is the indoor fan motor not turning as commanded. The higher numbers describe the outdoor side and the power electronics: compressor current, discharge temperature, pressure switches and the inverter board. Your model's manual or LG's guide gives the exact entry, and the entry for a portable unit is not always identical to the entry for a wall unit with the same number.
What an Owner Can Do for Each Family
Sensor codes deserve one reset and one look. Switch the unit off, unplug it or switch off its breaker if it is hard-wired, wait a few minutes and restore power. If the code returns, the sensor or its connector has failed and that is a technician part sitting inside the chassis. Fan-motor codes are worth a filter check first: with the unit switched off, slide the filter out of the front grille, wash it, dry it and refit it, because a filter packed with dust loads the fan until the control decides it is stalled. Also make sure nothing has fallen through the grille onto the blower. Communication codes on a split system are wiring or board faults between two units and are not owner work at all.
Codes That Point at the Sealed System
Any code about compressor current, discharge temperature or pressure describes the refrigeration circuit. There is nothing to reset that will change a refrigerant charge, a failed compressor or a blocked capillary. Handling refrigerant requires EPA certification under Section 608, the circuit is under pressure, and the outdoor side of a window unit contains the capacitor that starts the compressor. Do not remove the cabinet.
The Codes That Are Not CH
LG units also show a handful of messages without the CH prefix. FL and on some models CH04 report a full condensate tank on portable and some window units. A flashing filter indicator is a cleaning reminder that clears with a button press after the filter is washed. PO or SP on some displays reflects a mode setting rather than a fault. Confirm what you are looking at before treating it as a breakdown.
Restarts and Patience
After any power interruption, an LG compressor waits a protective interval of a few minutes before restarting, and during that time the fan may run while the air stays warm. A unit that seems to ignore the thermostat for three minutes after a reset is behaving correctly. Give it that time before judging whether a code has cleared.
What to Give the Technician
Note the full code including both digits, the type of unit, whether the fan runs, whether the outdoor side or the exhaust is blowing warm, and the model number from the plate on the chassis or behind the front grille. Book an LG air conditioner repair with those facts and the visit starts with the right family of components.