Panasonic CS-RE9SKUA, Service Manual

Page: 94 / 138

94
17.4.21 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
1 2 3
CN-HOT
(VH3-2)
4 WAYS
VALVE
For safety reason and to prevent component
breakdown, always switch off the power before
remove and connect the component.
When abnormality starts again.
Problem occurs in heating mode only?
4-way valve not working
(not energize).
Check V-coil attach to
solenoid valve.
Check valve v-coil
continuity.
Check CN-HOT
connection
(4-way valve connector).
Measure voltage
supplied to CN-HOT at
the start of heating.
Check the indoor pipe temperature
thermistor:
●
Plug out connector (CN-TH) from the
indoor unit PCB.
● Measure the resisitance of the indoor
heat exchanger temperature thermistor.
● Defect in indoor pipe temperature
thermistor.
● Replace the indoor pipe temperature
thermistor.
Outdoor PCB fault
●
Replace Outdoor PCB.
Reverse solenoid value faulty
●
Replace the 4-way valve.
● Reconnect CN-HOT
(4-way valve connector).
V-coil fault
●
Replace
V-coil only.
● Attach and screw the V-coil
to solenoid valve.
Remove CN-HOT.
Measure continuity
of the coil.
Outdoor PCB fault
●
Replace
Outdoor PCB.
No supply.
OK
OK (Depending on 4-way valve model).
OK
OK
YES
No
Good.
4 WAYS VALVE
COIL COMPLETE
YELLOW
YELLOW
CN-HOT
(WHT)
1
2
No
Good.
No
continuity
(open).
YES
YES
NO
NO
NO, it happen in cooling/dry as well.
● Check connecting tubes to 4-way valve.
Is the measured resistance of the indoor pipe
temperature thermistor matches the value
specified in its characteristic chart?
The 4-way valve may have been damaged or
wrongly connected between discharge and
suction tube.
Is 4-way solenoid valve being energised?
* Check gas side pipe – for hot gas flow in cooling mode