Panasonic CU-4E24RBU Service Manual

Also see for CU-3E19RBU: Operating instructions Service manual Service manual Service manual Installation manual

6815.2.13 H99 (Indoor Operating Unit Freeze Protection)Malfunction Decision Conditions During cooling operation, anti-freezing control take place when indoor pipe temperature is lower than 0°C (32°F).Malfunction Caused Clogged air filter of the indoor unit. Dust accumulation on the indoor unit heat exchanger. Air short circuit. Detection error due to faulty indoor pipe temperature sensor. Detection error due to faulty indoor unit PCB.TroubleshootingCheck the air filter.Clean the air filter.YesFor safety reason and to prevent componentbreakdown, always switch off the power beforeremove and connect the component.Is the air filter dirty?Check the dust accumulation onthe indoor unit heat exchanger.Is the indoor unit heatexchanger dirty?NoCheck the air passage.Provide sufficient airpassage.YesIs there any short circuit?NoCheck the indoor pipetemperature sensor.Replace the indoor unitPCB.YesDoes it conform to thesensor characteristic chart?NoClean the heat exchanger.YesNoReplace the indoor pipetemperature sensor.