What does a blinking light or CH code on my window air conditioner mean?

A flashing LED light or CH display on your LG or GE window air conditioner indicates a self-diagnostic error code. For example, on LG Dual Inverter units, CH01 indicates an indoor room thermistor fault, CH02 indicates an evaporator pipe thermistor fault, and CH21 indicates compressor overcurrent protection.

Can I reset a blinking AC error code by turning off the breaker?

Yes, turning off the breaker for 5 full minutes performs a hard microprocessor reset. If the error was caused by a transient power surge from the HECO grid, the unit may restart normally. However, if the light starts flashing again immediately upon powering on, a physical component failure exists that requires technician attention.

Diagnostic Fault Decoder • LG Dual Inverter & GE Window AC

Blinking Light Error Codes AC Repair Oahu

Is your window AC LED blinking in a repeated pattern or displaying a CH or F error code? Decode your diagnostic fault code below and schedule an on-site inspection or replacement consultation with our Oahu window AC specialists.

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The 5-Minute Power Reset Procedure

Voltage sags on the HECO power grid can lock up microprocessors. Unplug your window AC (or turn OFF its circuit breaker), wait 5 full minutes for memory buffers to clear, then plug it back in and press RESET on the plug head. If the error code flashes again, a physical sensor or board inspection is required.

Wait 5 Full Minutes

Discharges internal capacitors

Brand Guide

LG Dual Inverter Window AC Error Codes

CH01 / 1 Blink

Indoor Room Air Thermistor Open/Short

Technician Solution: Ohm-test room thermistor resistance (10k ohms at 77°F) and replace sensor clip.

CH02 / 2 Blinks

Evaporator Pipe Thermistor Error

Technician Solution: Inspect copper evaporator tube clip contact, test resistance (5k ohms at 77°F).

CH05 / 5 Blinks

Main Control Board to Inverter Module Signal Error

Technician Solution: Inspect internal wire harness between front display PCB and inverter control board.

CH06 / 6 Blinks

Inverter DC Peak / High Discharge Temperature

Technician Solution: Clean clogged condenser coils, verify fan blade rotation, and check inverter module.

CH21 / 21 Blinks

Compressor Overcurrent / Locked Rotor Protection

Technician Solution: Verify 115V/230V supply voltage, inspect inverter power board, or evaluate replacement.

Brand Guide

GE Window & Built-In Wall Sleeve Error Codes

F1 / E1

Room Temperature Sensor Fault

Technician Solution: Inspect front intake thermistor plug on control board and replace sensor if open.

F2 / E2

Evaporator Frost Sensor Fault

Technician Solution: Thaw frozen evaporator coil, clean air filter, and test coil thermistor resistance.

E4 / E5

Exterior Condenser Coil Over-Temperature / Fan Fault

Technician Solution: Clear exterior louver blockage, rinse salt-crusted condenser fins, and test fan motor.

FL / E8

Base Pan High Water Level / Drain Plug Alert

Technician Solution: Clear rear condensate drain port and verify 3/8-inch exterior tilt pitch.

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Schedule Error Code Diagnostic

Our technicians carry digital test equipment and can evaluate whether an in-place sensor fix or unit upgrade is most cost-effective.

Error Code FAQs

On LG Dual Inverter and GE digital window units, the LED display will show a 2-character code (such as CH01, CH02, CH21, F1, or F2) or blink the Clean Filter / Power LED in a repeating sequence. Count the flashes between pauses or note the digital code shown on the front panel.

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