LG Aircon CH90 / CH91 Error Code
Use this LG CH90 / CH91 error code guide to decide when to stop resetting, what to capture, and what to check before parts are quoted.
What Does LG CH90 / CH91 Mean?
LG CH90 / CH91 is listed as test-run piping connection issue. in Inverter Split, Multi-Split rows. The loaded row is source-backed by official diagnostic material. Confirm the exact model, series, or signal row before accepting a parts quote.
Indoor and outdoor unit capacity, jumper, model, or platform mismatch.
Incorrect setting after installation, PCB change, or mixed-system work.
Communication or board configuration issue if the setting is correct but the fault returns.
What To Do Now
Use these steps before another reset or parts quote.
Stop using the unit if CH90 / CH91 returns
If CH90 / CH91 returns after one reset, stop repeated restarts and get the matching source row diagnosed.
Reset CH90 / CH91 once
Capture the CH90 / CH91 display first, then power-cycle once only and note whether the same fault returns.
Send these to us
CH90 / CH91 error code, a clear display photo, LG model stickers, affected rooms, reset result, and recent installation, PCB, or model-pairing work
Send Us What You're Seeing
Share CH90 / CH91, your LG model, and what happened before it appeared. We'll read it and respond with the right next step before any work is approved.
What To Check Before Repair
Use this split to separate safe evidence capture from the tests a technician should prove before quoting parts.
| You Can Check | Technician Should Confirm |
|---|---|
| Before resetting CH90 / CH91, take a clear display photo. | Confirm the exact model pairing behind CH90 / CH91. |
| Capture the LG indoor and outdoor model stickers so the correct family row is used. | Check jumper caps, capacity settings, paired indoor/outdoor model compatibility, and recent board changes. |
| Note whether one room, several rooms, or the whole system is affected, plus whether it returns after one reset. | Only quote parts after configuration and communication checks are ruled out. |
What Changes The Next Step
These clues decide whether the first check is room-side, shared outdoor-side, refrigerant-side, source-table, or model-family confirmation.
| What You See | What It Points To |
|---|---|
| Only one indoor unit shows CH90 / CH91. | The affected room, indoor board path, wiring route, or local component should be checked first. |
| Several rooms or the outdoor unit show the same CH90 / CH91 fault. | The shared outdoor side, power path, communication trunk, or refrigerant circuit needs priority checking. |
| The fault returns immediately after one reset. | Start with the source-row diagnostic branch before approving parts. |
| The model family is different from the row you found online. | Use the model or series filter first; same-looking codes can still belong to different diagnostic tables. |
| The model belongs to Inverter Split, Multi-Split rows. | The loaded row is source-backed by official diagnostic material. Use the matching source row before quoting parts. |
Configuration Or Parts Decision
LG CH90 / CH91 can often be corrected by matching settings, model pairing, or board configuration. Parts should be quoted only after setup is confirmed.
Wrong capacity or pairing settings can mimic a hardware fault.
Recent installation, PCB replacement, or mixed-model work changes the first check.
Once configuration is confirmed, the diagnosis can move to wiring or board inputs.
Read Next
Use these if the quote mentions the parts, checks, or repair path this code points to.
Other LG Error Codes
If the code you're seeing isn't CH90 / CH91, jump to one of these or browse the full LG list.
Ready to Get Started?
Send the CH90 / CH91 error code, a clear display photo, and LG model sticker. Send the model sticker so the matching official row can be checked quickly. We can help separate setup, pairing, and hardware checks.