How do I fix LG LSU120HSV5 Ductless Mini Split Problems & Error Codes?

Follow the step-by-step diagnosis below. The most likely fix is identified by checking power, sensor resistance, and control-board signals in order — using a multimeter and the part numbers documented in the parts reference table.

Can I keep running the equipment with this fault active?

Generally no. Faults on Hvac units are emitted when a sensor, safety, or control circuit is outside its operating envelope. Running through an active fault risks compressor, heater, or control-board damage. Diagnose and clear the fault first.

What part is most commonly replaced for LG LSU120HSV5 Ductless Mini Split Problems & Error Codes?

The most frequently replaced parts for LG LSU120HSV5 Ductless Mini Split Problems & Error Codes are listed in the Parts Reference section of this guide with OEM part numbers and typical price ranges. Check the table for direct replacements.

Is LG LSU120HSV5 Ductless Mini Split Problems & Error Codes a DIY repair or do I need a technician?

Sensor swaps, fan motor replacements, and condenser cleaning are typical DIY-level repairs. Anything involving refrigerant, gas, or high-voltage (>240V) work requires a licensed technician for both safety and code-compliance reasons.

LG LSU120HSV5 Ductless Mini Split Problems & Error Codes

Q: What does LG LSU120HSV5 Ductless Mini Split Problems & Error Codes mean?

CH 05 communication error is most common on LSU120HSV5, usually caused by loose interconnect wiring or defective indoor/outdoor PCB.

LG LSU120HSV5 Ductless Mini Split Problems & Error Codes — Overview

The LG LSU120HSV5 is a ductless mini split air conditioner in the LS-HV/HSV single-zone family. The most frequent service call on this model is the CH 05 communication error, which indicates a breakdown in signal transmission between the indoor and outdoor units. This fault typically stems from field wiring problems at installation or from control board failure after several seasons of operation. LG’s diagnostic protocol for the LSU120HSV5 requires voltage and wiring verification before any board replacement, since loose or reversed interconnect wiring accounts for the majority of communication faults in this series. Other reliability issues include refrigerant leaks at flare connections, outdoor fan motor failures in high-use climates, and indoor blower bearing noise after extended runtime.

Jump to Common Problems

Most Common Problems on This Model

CH 05 communication error displayed on remote or indoor unit Loose, reversed, or damaged interconnect wiring between indoor and outdoor terminals causes loss of signal voltage, or a defective indoor PCB or outdoor PCB if wiring and supply voltage check out.
Unit not cooling or heating, no error code displayed Outdoor power supply voltage outside specification (1-phase 220 Vac ±10% or 3-phase 380 Vac ±10%) prevents normal operation, or a blown fuse on the outdoor PCB cuts power to compressor and fan.
Outdoor fan runs but compressor does not start Compressor start capacitor failure or compressor overload lockout stops the compressor while the fan circuit remains powered, or low refrigerant charge trips the low-pressure cutout.
Intermittent communication error after power cycle clears code External condensate pump or accessory wiring introduces electrical noise on the communication circuit, or corroded terminal connections at the outdoor unit cause intermittent contact.
Indoor unit blower runs but airflow is weak or noisy Clogged indoor evaporator coil restricts airflow and reduces cooling capacity, or worn indoor blower motor bearings produce grinding noise and reduced fan speed.
Refrigerant leak with gradual loss of cooling performance Improperly torqued flare connections at the indoor or outdoor service valves allow slow refrigerant migration, or a pinhole leak in the evaporator coil from corrosion requires coil replacement.
Outdoor unit does not receive power, indoor unit operates normally Open circuit breaker or disconnect at the outdoor unit cuts line voltage, or damaged field wiring between the indoor unit and outdoor unit interrupts power delivery.
Remote control displays error but system operates briefly then shuts down Defective outdoor temperature sensor sends incorrect readings to the outdoor PCB and triggers a safety shutdown, or high-pressure switch trips due to dirty outdoor condenser coil blocking airflow.

Parts That Commonly Fail

Part	Notes
Indoor PCB (main indoor control board)	Amazon \| Fails after communication circuit damage or power surge, diagnosed after wiring and voltage checks confirm no external faults.
Outdoor PCB (main outdoor control board)	Amazon \| Common failure point for CH 05 communication errors and compressor control faults, requires supply voltage verification before replacement.
Outdoor fan motor	Amazon \| Bearings wear in high-use climates, causing noise and reduced airflow across the condenser coil.
Compressor start capacitor	Amazon \| Degrades over time and prevents compressor startup while outdoor fan continues to run.

When to Call a Pro

Call a licensed HVAC technician for any CH 05 communication error after a simple power cycle does not clear the fault, since diagnosis requires multimeter checks of the communication signal voltage (0 to 65 Vdc on terminal N to 3 for split systems per LG guidance) and systematic isolation of the indoor or outdoor PCB. Refrigerant work, including leak detection, evacuation, and recharge, is also professional-only and requires EPA certification and recovery equipment. If you see sparking at terminals, smell burning plastic from a control board, or the outdoor disconnect trips repeatedly, shut off power at the breaker and call for service immediately to prevent further damage to the system.