LG Mini Split H91 Error Code

What H91 means

CH91, like CH90, is typically displayed during the test-run phase to prevent damage to the appliance, and on some models the same condition is displayed as F4. LG's response is identical for both codes: after installation or relocation, the piping connections should be checked by the installation technician; during normal use, a temporary fault from unstable power may be cleared with a 5-minute power-off reset. SplitAtlas describes CH91 identically to CH90 and marks it Stop use / Technician.

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.