Ariston AL03

Ariston error code AL03 indicates: Ariston Quadrio 4-Door Total NoFrost Refrigerator: Freezer compartment air ambient temperature sensor fault AL03; compressor runs continuously in emergency mode..

The primary root cause for Ariston code AL03 is: On Ariston refrigerators (Ariston Italian ergonomic chassis engineering and Bitron / EVO-II microprocessor bus platform): Open circuit or shorted NTC thermistor bead, damaged wiring behind rear freezer wall, or main board ADC port defect..

To resolve error code AL03: Isolate electrical supply. Measure air probe resistance across main PCB connector: ~32 kΩ at -18°C, ~16 kΩ at 0°C. If open/short, replace sensor. Press Alarm Reset button for 5 seconds to reset high-temperature acoustic warning and clear fault code.

Resetting power (unplugging for 5–10 minutes) clears temporary memory errors. However, if Ariston code AL03 persists, the physical component causing On Ariston refrigerators (Ariston Italian ergonomic chassis engineering and Bitron / EVO-II microprocessor bus platform): Open circuit or shorted NTC thermistor bead, damaged wiring behind rear freezer wall, or main board ADC port defect. must be inspected or replaced.

Set a digital multimeter to ohms (Ω). Disconnect power and test Compressor Motor Windings (Run/Start) & Defrost Heater across Across 3 compressor pins (Common, Run, Start): R(C-S) + R(C-R) = R(S-R). Winding to earth: >20MΩ (OL).. Expected nominal reading is 15Ω–25Ω (Run C-R), 20Ω–35Ω (Start C-S), 200Ω–400Ω (Defrost Heater). PTC Relay: 10Ω–30Ω at 25°C.. Tolerance: ±10%. Any low insulation resistance to casing (<2MΩ) trips the breaker. Defrost bimetal reads <0.5Ω when sub-zero..

Standard electrical safety protocol: 1. Disconnect 230V mains power before opening panels. 2. Verify zero voltage at test points. 3. Allow hot water or heating elements to cool below 30°C before handling.