Indoor unit stops cooling and displays E03; sometimes accompanied by ice on the indoor coil.

Safety first: Do not attempt to open refrigerant lines. Only certified refrigeration technicians should handle refrigerant.

• Step 1 – Check air filters: Turn off power, open the front panel of the indoor unit, and remove the filters. Clean them with mild soap and water, dry completely, and reinstall. Restricted airflow can cause coil icing and low-pressure trips.
• Step 2 – Inspect indoor coil: With the cover open, look for heavy ice buildup on the evaporator fins. If present, leave the unit OFF for several hours to allow full defrosting, then restart and observe.
• Step 3 – Look for oil stains: Around flare connections at the indoor and outdoor units, check for oily residue, which indicates a refrigerant leak. Note any suspected leak points.
• Step 4 – Reset and test: After defrosting and cleaning filters, restore power and run the unit. If E03 reappears, the system likely has a leak or metering device issue.
• Technician tasks: A technician should perform a leak test on the Ariston system, repair leaks (e.g., at flare joints or coils), evacuate, and recharge with the correct refrigerant type and weight, and test/replace the low-pressure sensor if needed.