Troubleshooting for Indoor Unit Si21-205156 Troubleshooting5.12 Transmission Error (Between Indoor and Outdoor Unit)RemoteControllerDisplayU4ApplicableModelsFFQ-B, FHQ-BUMethod ofMalfunctionDetectionMicrocomputer checks if transmission between indoor and outdoor units is normal.MalfunctionDecisionConditionsWhen transmission is not carried out normally for a certain amount of timeSupposedCauses Wiring indoor-outdoor transmission wire is incorrect. Failure of indoor unit PC board Failure of outdoor unit PC board Outside cause (noise, etc.) Power supply -open phaseTroubleshooting Diagnosis of incorrect or broken/disconnected wiringIf the LEDs on the indoor unit PC board are off, it indicates that the transmission wiring betweenindoor and outdoor units may be incorrect or broken/disconnected.Is HAP blinking? NONO (ON or OFF)YESIs HAP blinking?Is U4 displayednormally?Check forindoor unitmicrocomputernormal HAPYESTurn the power supply offonce and then back on.Faulty indoor unit PCboard or malfunction ofpower supply systemResets normally.Could result fromexternal cause(e.g. noise).To outdoor unit PCboardReplace the indoor unitPC board.(S2723)Measure the voltage between2 and 3 on terminal board.(Put minus (-) on 2 with amultiple meter set to DCrange.)Is the voltage10 V or less?YESNONOIs the voltage20 V or more?NOYESTo outdoor unitCautionBe sure to turn off power switch before connect or disconnect connector,or parts damage may be occurred.
