Unit stops and displays E4; may occur after running for some time, especially in cooling mode.

Safety first: Turn off power at the breaker. Do not attempt to open the sealed refrigeration system yourself; refrigerant work must be done by a licensed technician.

Steps to try:

• Clean the outdoor coil: Remove leaves, plastic bags, and debris from the condenser. Use a soft brush and low-pressure water to clean fins from inside out. Avoid bending fins.
• Check outdoor airflow: Ensure at least 30–60 cm of clearance around the unit and above it. Remove obstructions like plants or stored items.
• Verify outdoor fan operation: With power restored, observe the outdoor fan. If the compressor runs but the fan does not, turn power off again and inspect the fan motor and capacitor. Replace a seized fan motor or swollen capacitor.
• Inspect service valves: Confirm that any service valves on the outdoor unit are fully open (only if you can clearly identify them and they have not been tampered with).

When to call a technician: If E4 recurs after cleaning and verifying fan operation, a professional must check refrigerant charge, high-pressure switch, and system restrictions.