Indoor unit displays E5; compressor does not start or stops quickly; outdoor unit may not run.

Safety: Turn off the main breaker feeding the air conditioner. Verify power is off with a tester before touching terminals.

Steps:

• 1. Verify power supply: At the outdoor disconnect or breaker, confirm correct voltage and phase according to the Airwell nameplate. Incorrect supply can cause communication errors.
• 2. Inspect interconnecting cable: Open the indoor and outdoor electrical covers. Identify the communication terminals (often labeled 1-2-3 or L-N-S). Ensure the same wire colors are connected to the same terminal numbers at both ends.
• 3. Tighten terminals: Check for loose screws, burnt insulation, or discoloration. Tighten all terminal screws firmly but without over-torquing.
• 4. Check cable condition: Look along the cable route for mechanical damage, rodent bites, or water ingress. Replace the cable if insulation is damaged.
• 5. Polarity and wiring order: Many Airwell systems require correct polarity on communication lines. If wires are crossed between indoor and outdoor, correct them to match the wiring diagram on the unit.
• 6. Power cycle: After correcting wiring, turn power back on and wait 5–10 minutes for the system to re-establish communication. Observe if E5 clears.
• 7. PCB diagnosis: If wiring and supply are correct but E5 persists, either the indoor or outdoor PCB may be faulty. This requires advanced diagnostics (oscilloscope or manufacturer tools) and is best handled by an authorized technician.

Note: Never work on live terminals. If you are unsure about electrical work, contact a licensed electrician or Airwell technician.