The “BLDC” Motor Issue
CH 10 indicates a problem with the Indoor Fan Motor. Unlike older ACs, LG Inverter models use a high-tech BLDC (Brushless DC) motor. This motor has built-in electronics (Hall Sensors) that tell the PCB exactly how fast it’s spinning.
The Trigger: If the PCB sends a “Spin” command but doesn’t receive a speed signal back (Feedback) within a few seconds, it assumes the fan is dead or jammed and triggers CH 10 to protect the system.
1 DIY Checks (Before Calling Us)
The Pen Test
Turn the AC OFF. Open the flap. Use a pen to gently push the roller fan. Does it spin freely? If it feels stiff or jammed, the bearings are seized or something is stuck.
Listen for “The Jerk”
When you switch the AC on, does the fan make a slight “jerk” movement and stop? This means the motor is getting power but the magnetic rotor is failing to turn.
Rat Bite Check
The motor wire connector (usually on the right side of the PCB) is thin and fragile. Rats often chew through these 5 wires, cutting the feedback signal.
Atlas Aircon Diagnostics
How we pinpoint the CH 10 Fault:
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01.
Voltage Test (DC) We check the PCB connector pins. We need to see **310V DC** (High Voltage) and **15V DC** (Control Voltage). If voltages are missing, the PCB is dead.
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02.
Motor Replacement If the PCB is sending voltage but the fan doesn’t spin (or spins jerkily), the internal circuit of the BLDC motor is fried. Replacement is the only fix.
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03.
Blower Clean & Balance Sometimes, heavy dust makes the blower so heavy that the motor overloads trying to spin it. A deep jet-pump service can sometimes solve CH 10.
Estimated Repair Cost (Atlas Aircon)