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TROUBLESHOOTING
(5) Checking Method of Electronic Expansion Valve
Indoor Unit Electronic Expansion Valve Outdoor Unit Electronic Expansion Valve
Locked Check for the liquid pipe temperature It is abnormal if the liquid pipe pressure
with during heating operation. does not increase during cooling
Fully Closed It is abnormal if the temperature does operation.
not increase.
Locked It is abnormal under the following It is abnormal if the liquid pipe pressure
with conditions; The temperature of freeze does not increase and the outlet
Slightly Open protection thermistor becomes lower temperature of the expansion valve
than the suction air temperature when decreases after the cooling operation
the unit under checking is stopped and is started.
other units are under cooling operation.
Locked It is abnormal under the following
with conditions; After heating operation for
Fully Open more than 30 min., the discharge gas
tem
ressor is not 10
o
C
higher than the condensing temperature
and there is no other faults such as
excessive charge of refrigerant, etc.
(l) By touching the + side of the tester to the RB terminal
of ISPM and the - side of tester to N terminal of ISPM.
If the resistance is more than 90 kΩ, it is normal.
(m) By touching the - side of the tester to the RB terminal
of ISPM and the + side of tester to N terminal of ISPM.
If the resistance is more than 90 kΩ, it is normal.
TB3
+
-
RS W
RB
VTU
NPD P
TB2
R216
R215
ZN20
LED201
ZN202
R201
R200
CN207 CN206
CN9
PC207
C
PC208
CN8
RB
N
P
P1
RB
N
TB3
+
-
RS W
RB
VTU
NPD P
TB2
R216
R215
ZN20
LED201
ZN202
R201
R200
CN207 CN206
CN9
PC207
C
PC208
CN8
RB
N
P
P1
RB
N
Unit
Under
Checking
Electronic Expansion Valve
Freeze Protection
Thermistor
Other
Units
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