The LG LMU24CHV is a multi-zone, high-efficiency ductless mini-split air conditioning system. This service manual provides authorized technicians with essential information for installation, maintenance, troubleshooting, and repair. It covers system specifications, wiring diagrams, refrigerant handling, error codes, and safety procedures. Below are key sections for safety, technical data, installation, operation, maintenance, and troubleshooting.
WARNING: Only qualified personnel should perform installation and service. Disconnect all power before servicing.
| Hazard | Precaution |
|---|---|
| Electrical Shock | Verify power is OFF using a voltmeter before touching terminals. |
| Refrigerant | Wear safety goggles and gloves. Recover refrigerant; do not vent to atmosphere. |
| Heavy Lifting | Use proper equipment or multiple persons to lift outdoor/indoor units. |
| Sharp Edges | Wear cut-resistant gloves when handling coil fins or sheet metal. |
| High Pressure | Use rated gauges and hoses. Release pressure slowly in a ventilated area. |
Key components: Outdoor Unit (Compressor, Fan, Coil, PCB), Indoor Unit(s) (Blower, Coil, Drain Pan, Filters), Remote Controller, Interconnecting Cables & Refrigerant Lines.
Select location with adequate clearance for airflow and service access.
CAUTION! Do not bend refrigerant lines sharply. Use proper torque on flare nuts.
Refer to diagrams on pages 12-15 of manual. Main power connects to terminal block (L1, L2, Ground) in outdoor unit.
| Component | Specification |
|---|---|
| Compressor | RLA: 12.5A, LRA: 78A |
| Outdoor Fan Motor | 1/3 HP, Capacitor: 5 µF |
| Indoor Blower Motor (each) | ECM, 120V, 0.8A |
| Control PCB Fuse | 3.15A, 250V (on outdoor PCB) |
Note: Use copper conductors only. Size per NEC and unit nameplate.
Use remote or wall controller to set mode (Cool, Heat, Dry, Fan, Auto), temperature, fan speed (Auto, Low, Med, High), and vane direction.
Advanced Settings (Service Tool): DIP switches and PCB jumpers for addressing indoor units, thermostat adjustment, fan delay, and filter timer reset.
Test Mode: Press and hold remote "Temp Down" and "Mode" buttons for 5 seconds to enter compressor test run.
Regular maintenance ensures efficiency and longevity.
WARNING! Disconnect power before any maintenance.
Required tools: Manifold gauge set for R-410A, vacuum pump, electronic scale, leak detector.
LED flashes on indoor/outdoor PCB indicate fault. Use remote or service tool to read detailed code.
| Code | Description | Possible Cause |
|---|---|---|
| CH 00 | Communication Error | Wiring fault, faulty PCB, power surge |
| CH 10 | High Pressure Fault | Dirty coil, restricted airflow, overcharge |
| CH 20 | Low Pressure Fault | Refrigerant leak, restriction, faulty sensor |
| CH 31 | Inverter Compressor Fault | PCB, compressor, power supply issue |
| CH 70 | Indoor Fan Motor Lock | Motor failure, obstruction, capacitor |
Reference diagrams for part numbers. Major components:
Note: Always verify part number with unit serial number before ordering.
| Symptom | Possible Cause | Corrective Action |
|---|---|---|
| Unit not turning on | No power, blown fuse, faulty remote | Check disconnect, breaker, and fuse. Replace remote batteries. |
| Insufficient cooling/heating | Dirty filters, low refrigerant, incorrect mode | Clean filters. Check charge and pressures. Verify mode setting. |
| Water leaking indoors | Clogged drain line, improper slope, frozen coil | Clear drain line. Ensure proper slope. Check for low charge. |
| Unusual noise | Loose parts, debris in fan, vibration | Tighten screws and mounting. Clean fan blades. Check isolators. |
| Error code displayed | System fault per code table | Refer to Error Code Diagnostics section (Section 9). |
Reset: Power cycle unit (turn off at disconnect for 5 minutes).
Technical Support: LG Electronics USA, 1-800-243-0000; www.lg.com