Panasonic CS-E18SD3UAW service manual - Page 87

15.5.16 F11 (4-way Valve Switching Failure) Malfunction Decision Conditions  When indoor heat exchanger is cold during heating (except deice) or when indoor heat exchanger is hot during cooling and compressor operating, the 4-way valve is detected as malfunction. Malfunction Caused  Indoor heat exchanger (pipe) thermistor  4-way valve malfunction Troubleshooting When abnormality starts again Check the indoor pipe temperature thermistor: Plug out connector (CN-TH) from the indoor unit PCB Measure the resistance of the indoor heat exchanger temperature thermistor For safety reason and to prevent component breakdown, always switch off the power before Caution remove and connect the component. Is the measured resistance of the indoor NO pipe temperature thermistor matches the value specified in its characteristic chart? YES Problem occurs in heating mode only? Defect in indoor pipe temperature thermistor Replace the indoor pipe temperature thermistor YES NO, it happen in cooling/dry as well Is 4-way solenoid valve being energised? NO YES Outdoor PCB fault Replace Outdoor PCB The 4-way valve may have been damaged or wrongly connected between discharge and suction tube Check connecting tubes to 4-way valve 4-way valve not working (not energize) Check CN-HOT connection (4-way valve connector) 4 WAYS VALVE YELLOW YELLOW COIL COMPLETE 1 CN-HOT (WHT) 2 No Good Reconnect CN-HOT (4-way valve connector) OK No Check V-coil attach to solenoid valve Good Attach and screw the V-coil to solenoid valve OK No continuity Check valve v-coil continuity (open) V-coil fault Replace Remove CN-HOT. V-coil only CN-HOT (VH9-2) 123 Measure continuity OK of the coil 4 WAYS VALVE Measure voltage supplied to CH-HOT at the start of heating OK (Depending on 4-way valve model) Reverse solenoid valve faulty Replace the 4-way valve No supply Outdoor PCB fault Replace Outdoor PCB * Check gas side pipe - for hot gas flow in cooling mode 87