ESIE09-08 Troubleshooting by Indication on the Remote ControllerTroubleshooting 1993.56 “U4” Malfunction of Transmission Indoor UnitRemote ControlDisplayU4Subcode 4ApplicableModelsAII indoor unit modelsMethod ofMalfunctionDetectionMicrocomputer checks QA communication of indoor unit.MalfunctionDecisionConditionsWhen transmission is not carried out normally for a certain amount of timeSupposedCauses Wrong wiring between indoor unit PC boards. [A4P (1ø) or A5P (3 ø)] and A1PTroubleshootingCautionReplace indoor unit PCboardCorrect the wiringYESNOIs the wiring("1-2-3" communicationand upwiring)normal?Be sure to turn off power switch before connecting or disconnecting connector,otherwise parts may be damaged.
