Hitachi FSXN Series Service Manual page 276

8 Troubleshooting
When measuring, check the multimeter probe colour and the terminals to be measured as shown in the table below.
Fan controller
R
T
P1
S
(*) Stay on for at least 30 seconds when measuring the following terminals.
< Initial DSW setting >
DSW1
1 2
OFF OFF
Regarding the DSW setting, do not change the original setting. If the settings are modified, transmission anomalies and fan
controller failure may occur.
(7) Method for checking the electronic expansion valve
Check the temperature of the liquid pipe during the heating
Locked with fully closed operation. If the temperature does not increase, this is
abnormal.
It is abnormal under the following conditions:
Locked with slightly open The temperature of the freeze protection thermistor is
lower than the temperature of the suction air when the unit
under checking is stopped and other units are operating in
cooling.
Locked with fully open
270
SMGB0065 rev. 1 - 12/2010
Multimeter probes
Red (+) - Black (-)
N
P2
LED501
ON
1 1 2 3 4 2 3 4
3 4
OFF OFF
Indoor unit electronic expansion valve
Electronic Expansion Valve
Freeze Protection
Thermistor
Unit Other
Under Units
Checking
P1 - R
P1 - S
P1 - T
R - N
S - N
T - N
P1 - U
P1 - V
P1 - W
U - N
V - N
W - N
R - P1
S - P1
T - P1
N - R
N - S
The resistance will gradually increase
N - T
after it is between 1700 kΩ to 1900 kΩ
U - P1
(*)
V - P1
W - P1
N - U
N - V
N - W
Outdoor unit electronic expansion valve
It is not abnormal if the pressure of the liquid pipe does not
increase during the cooling operation.
It is abnormal if the pressure of the liquid pipe does not
increase and the expansion valve outlet temperature
decreases after the cooling operation is started.
It is abnormal under the following conditions:
After heating operation in the heating mode for longer than
30 minutes, the compressor discharge gas temperature is
not 10°C higher than the condensing temperature and there
are no other problems such as excessive refrigerant charge,
etc.
Resistance range
1 kΩ and over