Heater runs briefly then stops with E04 on the display

Safety first: Turn off power at the breaker before removing any panels. Do not tamper with refrigerant charge or sealed components.

• Inspect and clean air coil: Remove debris from the outdoor coil using a soft brush and gentle water spray. Clean both sides if accessible.
• Check condenser fan operation: Restore power briefly and observe if the fan starts when the compressor runs. If the fan does not spin, turn power off immediately to avoid damage.
• Check for obstructions: Ensure there is adequate clearance around the heater for air intake and exhaust. Remove any covers, foliage, or objects blocking airflow.
• Inspect fan motor wiring: With power off, check the fan motor connector and wiring harness for loose or damaged wires. Reseat connectors.
• Restart and monitor: After cleaning and verifying fan operation, restart the heater and monitor pressure-related error behavior.

If E04 returns and the fan is running with clean coils, the high-pressure switch or refrigerant charge may be at fault. A certified technician should test the high-pressure switch and system pressures.