Outdoor unit stops and E3 appears; unit may start then quickly shut down in cooling mode

Safety first: Turn off power at the breaker before working on the outdoor unit. Do not attempt to open the sealed refrigeration system yourself.

Steps to check:

• 1. Clear obstructions: Ensure at least 60–100 cm clearance around the outdoor unit. Remove leaves, plastic bags, or debris blocking the air inlets and outlets.
• 2. Clean condenser coil: Remove the outdoor unit top or side grille as per the service manual. Use a soft brush or low-pressure water spray from inside out to clean the condenser fins. Avoid high-pressure washers that can bend fins.
• 3. Check outdoor fan operation: Restore power and briefly run the unit while observing the outdoor fan (keep hands clear). If the compressor runs but the fan does not spin or is very slow, turn power off immediately. A failed fan motor or capacitor can cause high pressure and E3.
• 4. Check for heat buildup: If the unit is installed in a confined balcony or box, improve ventilation or shade to reduce recirculation of hot air.

When to call a technician: If the fan and coil are clean and E3 persists, the system may be overcharged, have a blocked refrigerant circuit, or a faulty high-pressure sensor. These require professional gauges and tools to diagnose and repair.