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LG · Split air conditioners · LG wall-mounted Inverter air conditioners (RAC) – CH codes

CH90Test-run protection (piping connections)

Name in the manufacturer's documentation (service manual): Test-run protection (piping connections)[1]

In plain words (editorial)

Test-run protection related to the piping connections. LG says CH90/CH91 are typically shown during the test run to prevent damage to the appliance; the piping connections should be checked.

When to call a service technician: Consult the installation technician.

✎ editorial – written from the cited sources, not a manufacturer statement. Status: draft.

The Polish page has more detail (plain-language explanation, safe checks, guides): Read in Polish →

Sources

Every statement has a footnote to the document and PDF page. “Quote verified” means the quote was found automatically in the text of that page.

  1. [1] LG USA Support – [LG Air Conditioner] Guide to Error Codes (help library, 2026-02-23) – text capture , p. 2 official manufacturer document quote verified CH90 / CH91 errors are typically displayed during the test run phase to prevent damage to the appliance.
  2. [2] LG USA Support – [LG Air Conditioner] Guide to Error Codes (help library, 2026-02-23) – text capture , p. 2 official manufacturer document quote verified ch90 / ch91 errors are typically displayed during the test run phase
  3. [3] LG USA Support – [LG Air Conditioner] Guide to Error Codes (help library, 2026-02-23) – text capture , p. 2 official manufacturer document quote verified the piping connections should be checked.
  4. [4] LG USA Support – [LG Air Conditioner] Guide to Error Codes (help library, 2026-02-23) – text capture , p. 2 official manufacturer document quote verified please consult the installation technician.