LG Mini Split H21 Error Code

Updated 2026-08-30 · review status: manual-verified · reviewed by MiniSplitDecoder Editorial Team Last verified: 2026-08-30

Check your model first

  • SplitAtlas (LG support table, Mega R-32)
  • Snowflake Aircon / Beacon Saves (wall-mounted rows)
  • Heat Pump Answers

Match the model on your equipment label to the linked manufacturer documentation. The same code can mean different things across model families.

Quick answer

LG H21/CH21 means an outdoor inverter power-module (IPM) or compressor-drive overcurrent fault - the inverter detected excessive DC-peak or IPM current and shut the compressor down. Reset once at the breaker; if H21 returns, stop and call a licensed HVAC technician. Compressor, inverter-board, and electrical work are not homeowner repairs.

Severity: high · DIY difficulty: easy

Safety

Stop at the breaker power-cycle and any plug-accessible checks (filters, remote settings, visible wiring). The outdoor unit's capacitor holds a lethal charge and the refrigerant circuit is both pressurized and (on R-32 units) flammable — opening panels or servicing the sealed system is licensed-technician work (EPA 608).

What H21 means

H21 (CH21) means an outdoor inverter overcurrent / DC-peak / IPM (intelligent power module) protection fault: the compressor-drive electronics detected current above the safe limit and stopped the compressor. LG's own single-split troubleshooting material groups CH21 with inverter compressor-drive faults (CH21/CH26/CH27/CH29), and LG's support table points to compressor or inverter PCB failure. Multiple code references agree on the compressor-inverter overcurrent reading, with wording varying by series ('IPM over-current', 'DC-peak or IPM protection', 'inverter power module fault').

Code meaning varies by series

  • SplitAtlas (LG support table, Mega R-32): CH21 = outdoor inverter compressor IPM failure - compressor or inverter PCB failure, not a homeowner repair
  • Snowflake Aircon / Beacon Saves (wall-mounted rows): CH21 = outdoor inverter DC-peak or IPM protection fault; Multi V 5 VRF uses 211/212/213 frame suffixes for inverter-board IPM overcurrent
  • Heat Pump Answers: CH21 = compressor inverter (IPM) over-current - power off, technician (compressor)

First checks before service

This page currently documents the safe reset triage. If the code returns, use the linked source manual or a qualified technician for code-specific diagnosis.

  1. 1. One-time fault event (power disturbance or transient sensor reading) common DIY

    Check: Power-cycle at the breaker/disconnect (or unplug for CPAP), restore, and run the system while watching for the code.

    Fix: If the code does not return after a full run cycle, the fault was transient — monitor, no repair needed.

  2. 2. Fault persists after a clean reset occasional pro only

    Check: If the code returns immediately or every session, note the conditions (startup, heating, after rain).

    Fix: A persisting code points at the component the manual assigns to this code — that repair is technician territory.

Related codes

Cross-references for the same fault family, by brand:

LG H23 · LG H27 · LG H26

Commonly searched as: "lg h21" · "lg error code h21" · "lg air conditioner h21"

Sources

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