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LG Air Conditioner CH21 / CH23 / CH26 / CH29 Error Code

Outdoor compressor or drive circuit fault. Here is what it means and how to clear it, easiest fix first.

CH21 / CH23 / CH26 / CH29
May need a pro

The outdoor unit has flagged a problem with the compressor or the circuit board that controls it. A short-lived power problem can set it off; so can a compressor that is failing, a fault in the circuits that drive and protect it, or another faulty electrical part in the outdoor unit.

Some models show E9 for this group of faults. LG does not break down each code individually on its US pages. LG says its error-code guide covers all models, so the exact code and its meaning can differ on yours; check your owner's manual.

Safety first: unplug the air conditioner (or switch off its breaker) before touching filters, hoses or panels. If you smell burning or gas, or see water near the outlet, stop and call a professional.

How to fix LG CH21 / CH23 / CH26 / CH29

  1. Reset the power at the breaker

    Switch off the breaker that feeds the air conditioner (some systems have separate breakers for the indoor and outdoor units, so switch off both). Wait about five minutes, switch the power back on and restart the unit to see if the code clears.

  2. Stop if the code comes straight back

    If the code reappears after the reset, LG advises stopping use of the unit. Leave it switched off rather than restarting it again and again, since repeated restarts against a compressor fault can cause more damage.

When to call a technician

Repeated compressor or inverter codes need a technician. LG warns against opening the unit or replacing internal parts yourself because of the risk of electric shock and fire.

Parts that commonly cause CH21 / CH23 / CH26 / CH29

Order parts by your exact model number so they fit.

Other LG air conditioner codes

Frequently asked questions

What does CH21 / CH23 / CH26 / CH29 mean on a LG air conditioner?

The outdoor unit has flagged a problem with the compressor or the circuit board that controls it. A short-lived power problem can set it off; so can a compressor that is failing, a fault in the circuits that drive and protect it, or another faulty electrical part in the outdoor unit.

Can I fix LG CH21 / CH23 / CH26 / CH29 myself?

Only the basic checks. You can safely try the steps above, but CH21 / CH23 / CH26 / CH29 usually points to a part or fault that needs a technician.

What if CH21 / CH23 / CH26 / CH29 keeps coming back?

A code that returns after a reset and the checks above usually means a part is wearing out. Note when CH21 / CH23 / CH26 / CH29 appears (which cycle, how often) and have your model number ready; it helps a technician bring the right part on the first visit.

Last reviewed 2026-10-19. Codes and steps can vary by model; check your owner's manual.

References