LG AC Error Code CH12: What It Means and How to Fix It Fast

🔧 Error Snapshot

• Error Code: CH12

• Type: Communication failure

• Affected Parts: Indoor + Outdoor unit

• Severity: Medium (fixable in most cases)

🧭 How to Identify the Problem (Decision Flow)

Follow this simple path:

➤ Step 1: Is the Outdoor Unit Running?

• Yes → Go to Step 2

• No → Likely power supply or wiring issue

➤ Step 2: Does the Error Appear Immediately?

• Yes → Communication wiring or PCB issue

• No (after some time) → Possible overheating or intermittent fault

➤ Step 3: Any Voltage Fluctuation?

• Yes → Electrical issue

• No → Internal hardware issue

🔍 Deep Dive into Causes

1. Communication Wire Failure

The cable connecting indoor and outdoor units may:

• Be loose

• Be incorrectly connected

• Have internal damage

2. Indoor PCB Not Sending Signal

The indoor control board may fail to transmit data.

3. Outdoor PCB Not Responding

The outdoor unit may receive signals but not respond.

4. Power Imbalance

If the outdoor unit is not getting proper voltage, communication breaks.

5. Environmental Damage

• Rainwater leakage

• Dust buildup

• Rodent-damaged wires

🛠️ Practical Fixes (In Order)

🔹 Fix 1: Full System Reset

• Turn off AC

• Switch off MCB (main breaker)

• Wait 10 minutes

• Restart

🔹 Fix 2: Check Outdoor Unit Activity

• If silent → power issue

• If running → communication issue

🔹 Fix 3: Inspect Communication Cable

• Tighten all terminals

• Replace damaged wires

• Ensure correct wiring sequence

🔹 Fix 4: Stabilize Power Supply

• Install voltage stabilizer

• Avoid using AC during heavy fluctuations

🔹 Fix 5: PCB Inspection

• Requires technician

• May involve:

  • Repair

  • Replacement

🚨 When It’s Serious

Call a technician immediately if:

• PCB is suspected

• Wires are burnt

• Outdoor unit is completely dead

• Error persists after all fixes

🛡️ Prevention Checklist

• ✔ Get AC serviced every 6 months

• ✔ Use proper earthing and stabilizer

• ✔ Protect outdoor unit from rain

• ✔ Ensure professional installation

💡 Final Insight

CH12 is not about cooling—it’s about communication failure between two systems.

Fix the signal, and the cooling comes back.

Read More:

LG AC error code CH02

LG AC error code CH41

LG AC error code CH61