Indoor unit will not start; display shows E101 shortly after power-on.

Safety first: Turn OFF the circuit breaker for the air conditioner and verify power is off before removing any covers. Risk of electric shock.

• Step 1 – Power reset: Turn the AC off at the remote, then switch off the breaker for 5 minutes. Turn the breaker back on and restart the unit. If E101 clears and does not return, it may have been a transient communication fault.
• Step 2 – Check model compatibility: Confirm the indoor and outdoor units are a matched Samsung pair (model numbers from the rating labels). Mismatched units can trigger communication errors.
• Step 3 – Inspect communication cable:
  • Remove the front cover of the indoor unit (wall-mount) and access the terminal block.
  • Verify that the communication terminals (often labeled 1–2–3 or L–N–S) are wired identically at both indoor and outdoor units.
  • Tighten any loose screws and ensure no burnt or discolored wires.
• Step 4 – Check polarity and grounding: Ensure live (L), neutral (N), and signal (S) are correctly connected and that the ground wire is properly attached.
• Step 5 – Inspect PCBs (visual only): With power still OFF, remove the outdoor unit service panel and visually inspect the outdoor PCB for burnt components, bulged capacitors, or signs of moisture damage. Do not touch components unnecessarily.
• When to call a technician: If wiring is correct and secure but E101 persists, the indoor PCB or outdoor PCB may be defective and require professional diagnosis and replacement.