LG Mini Split H90 Error Code

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

Check your model first

  • During commissioning / after install or relocation
  • Some models
  • During normal use

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

Quick answer

CH90 is shown during LG's test-run/commissioning phase to protect the appliance (on some models displayed as F4). If it appears after installation or relocation, have the installer check piping connections; during normal use, one power-cycle, then service if it returns.

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 H90 means

CH90 is typically displayed during the test-run phase to prevent damage to the appliance; on some LG models the same condition is displayed as F4. LG's guidance: if the error appears shortly after installing or relocating the unit, the piping connections should be checked by the installation technician; in normal use it may be a temporary fault from unstable power, cleared by a 5-minute power-off reset. SplitAtlas describes CH90 the same way and marks it Stop use / Technician.

Code meaning varies by series

  • During commissioning / after install or relocation: Test-run protection - piping connections must be inspected by the installer
  • Some models: Same condition displayed as F4
  • During normal use: Possibly temporary, from unstable power or electrical factors; do not ignore recurrence

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 H91 · LG F4 · LG H93 · LG H66

Commonly searched as: "lg h90" · "lg error code h90" · "lg air conditioner h90"

Sources

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