HVAC Code Lookup

LG Mini-Split Code CH51

Hard lockoutShown as: Outdoor LED01 (red) blinks 5 times, LED02 (green) blinks 1 time

Over capacity / combination ratio out of range. The total capacity of the connected indoor units is under 50% or over 130% of the outdoor unit's capacity. On multi-zone systems this is an installation or wiring mistake, not a component failure.

Manual wording: “Combination ratio (capacity) is out of range; Total nominal indoor unit capacity is <50% or >130% of the outdoor unit capacity”

Documented for: LG Multi F / Multi F MAX multi-zone systems, and single-zone systems with a mismatched indoor/outdoor pair

Likely causes, most common first

  1. Mis-wiring between indoor and outdoor units
  2. Wrong wiring or piping connection during installation of several similar models at the same site (zone A's pipe run connected to zone B's wiring)
  3. Indoor units connected that add up to too little or too much capacity for the outdoor unit

When to call a technician

CH51 means the system was put together in a combination LG does not allow, or the zone wiring and piping were crossed at install. The installer needs to come back and verify each indoor unit's wiring matches its piping.

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