HVAC Code Lookup

LG Mini-Split Code CH21

Hard lockoutShown as: Outdoor LED01 (red) blinks 2 times, LED02 (green) blinks 1 time

DC Peak / IPM fault. The inverter power module in the outdoor unit saw a current or voltage spike from the compressor and shut itself down to protect the board. Most often the system is being asked to work against blocked airflow or is short on refrigerant.

Manual wording: “DC Peak (IPM Fault); Compressor DC voltage was too high”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Overload operation - indoor or outdoor fan restricted, screened or blocked, or a refrigerant cycle issue
  2. Refrigerant leak
  3. Disconnection or short circuit inside the compressor
  4. Compressor failure
  5. Burned parts inside the PCB (IPM failure)

What you can safely check yourself

  • Clear leaves, grass clippings, snow, or anything stacked against or on top of the outdoor unit
  • Check and clean the indoor air filters
  • Make sure the indoor supply and return grilles are open and unblocked
  • Turn the system off at the breaker for three minutes and back on (the boards need three minutes to fully discharge)

When to call a technician

If airflow is clear and CH21 returns, the compressor, its wiring, or the inverter board is failing. That is high-voltage inverter work - call a technician.

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