SiUS12-814 TroubleshootingService Diagnosis 1255.9 Freeze-up Protection ControlRemoteControllerDisplayA5Outdoor Unit LEDDisplayA 5 1 4 2 1 3 4 4 4Method ofMalfunctionDetectionIndoor unit icing, during cooling operation, is detected by checking the temperatures sensed by theindoor unit heat exchanger thermistor and room temperature thermistor that are located in a shut-down room.MalfunctionDecisionConditionsIn the cooling mode, the following conditions (A) and (B) are kept together for 5 minutes.(A) Indoor unit heat exchanger temperature ≤ 30°F(B) Indoor unit heat exchanger temperature ≤ Room temperature Δ–18°F If the indoor unit icing protector is activated four times straight, the system will shut down.(The 4-time counter will reset itself if any of the following errors does not occur during thecompressor running time (total time): OL, radiation fin temperature rise, gas shortage, andcompressor startup.)SupposedCauses Wrong wiring or piping EV malfunctioning in each room Short-circuit Indoor unit heat exchanger thermistor defective Indoor unit thermistor defective
