Panasonic WH-MHF09G3E5 Service Manual page 89

16.5.5 Service Valve Error (H27)
Malfunction Decision Conditions:
During cooling operation, when:-
[a] Indoor refrigerant pipe temperature at compressor startup - present indoor refrigerant pipe temperature < 2°C
[b] Present high pressure - high pressure at compressor startup < 5kg/cm²
**Judgment only for first time cooling operation and not during pump down operation.
Malfunction Caused:
1 3 way valves closed.
2 Faulty high pressure sensor.
3 Faulty indoor refrigerant pipe temperature sensor
4 Faulty outdoor unit PCB (main).
Abnormality Judgment:
Continue for 5 minutes.
Troubleshooting:
Turn ON the power and measure the DC
voltage pin 1 & 3 (GND) of CN-HPS before
Check the 3 way valves.
Is the 3 way valve closed?
No
Check for clogged
expansion valve or strainer.
Is the expansion valve or
strainer clogged (ice formed)?
No
Check the indoor ref. pipe
temperature sensor.
Does it conform to the
sensor characteristic chart?
Yes
and after run the system.
Is the measured voltage
before and after run the
system unchanged?
Yes
For safety reason and to prevent component breakdown,
always switch off the power before remove and connect the component.
Yes
Open the 3 way valve.
- Replace the expansion
Yes
valve and/or strainer.
- Reclaim and recharge
refrigerant.
No
Replace the indoor ref. pipe
temperature sensor.
- Defect in outdoor unit
No
PCB (main).
- Replace the outdoor
unit PCB (main).
- Defect in outdoor high
pressure sensor.
- Replace the outdoor
high pressure sensor.
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