Unit stops and displays E04; sometimes occurs during very hot operation or after long runtime.

Safety first: Isolate power at the breaker before touching the outdoor unit. Compressor terminals carry high voltage.

• Step 1 – Improve ventilation: Ensure the outdoor Ariston unit is not installed in a confined space. Remove any objects blocking airflow and provide shade if exposed to direct sun, without blocking vents.
• Step 2 – Clean condenser coil: With power OFF, remove the protective grille and clean the coil fins using a soft brush or low-pressure water. Let the unit dry before restoring power.
• Step 3 – Check outdoor fan: Restore power and run the unit. Confirm the outdoor fan starts immediately with the compressor. If the fan is not running or is noisy, turn power off and inspect the fan motor and capacitor. Replace if seized or burnt.
• Step 4 – Allow cool-down: Leave the system off for 30–60 minutes to allow the compressor thermal protector to reset, then restart.
• Technician tasks: If E04 persists, a technician should check compressor current draw, verify refrigerant charge, and test the compressor thermal protector and windings.