HVAC Code Lookup

LG Mini-Split Code CH05

Soft lockoutShown as: Indoor unit LED1 (units place) blinks 5 times

Communication error between the indoor unit and the outdoor unit. The indoor unit's control board is not receiving a signal from the outdoor unit. This is the single most common LG mini-split code and it usually means the outdoor unit has no power or the interconnecting wiring is wrong or loose.

Manual wording: “Indoor unit PCB is not receiving signal from outdoor unit.”

Documented for: All LG residential mini-splits, single-zone and multi-zone

Likely causes, most common first

  1. No power on the indoor unit
  2. Indoor/outdoor unit power connection error, or the communication line was never installed
  3. Improper connection at the terminal block for the communication wire
  4. Improper wiring of the communication L-N wire between indoor and outdoor units
  5. Communication error caused by external electrical noise
  6. Indoor/outdoor communication circuit parts burned, or no power due to a burned indoor or outdoor PCB

What you can safely check yourself

  • Check the breakers for BOTH the indoor and outdoor unit are on and not tripped
  • Check the outdoor disconnect switch next to the condenser is switched on
  • Turn the system off at the breaker for one minute, then back on

When to call a technician

If power is confirmed on at both units and CH05 stays, the interconnecting communication wiring or one of the control boards is at fault. Terminal-block and low-voltage work is a technician job.

A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Other LG codes