Freezer shows error code A4 and may not maintain the set temperature; display may flash.

Safety first: Unplug the appliance before accessing any control panels or wiring.

• Locate the ambient sensor: On many Ariston freezers, the cabinet or ambient NTC is located behind the internal liner or near the air channel at the top or side of the compartment.
• Inspect wiring: Remove the relevant cover or trim to access the sensor. Check for pinched, cut, or discolored wires. Ensure the connector is fully seated on the control board.
• Clean and reseat: If there is oxidation on the connector, gently clean with electrical contact cleaner (with power disconnected) and reconnect firmly.
• Test sensor (optional): Use a multimeter to measure resistance at room temperature. Compare with expected NTC values from the service documentation if available. Replace if open or shorted.

When to call a technician: If replacing the sensor does not clear the A4 error, the main PCB may need professional diagnosis and replacement.