Hitachi RAS-10HRNM, Руководство по обслуживанию, Страница: 329 / 482

• Checking procedure for the electronic expansion valve
Valve position Electronic expansion valve Outdoor unit electronic expansion valve
Locked fully closed
Check the temperature of the piping in the
heating process. Failure of the temperature to
rise indicates a fault.
It is abnormal if the liquid pipe pressure does not
increase during the cooling process.
Locked slightly open
The following conditions indicate a fault:
–
Where the freeze protection thermistor
temperature is lower than the intake air
temperature.
– Where the unit being inspected stops and
other units continue operating in cooling
mode.
Electronic expansion valve
Freeze protection thermistor
It is abnormal if the liquid pipe pressure does not
increase and the outlet temperature of the
expansion valve decreases after the cooling
process starts.
Locked fully open
It is abnormal under the following conditions:
after the heating process for more than 30
minutes, the discharge gas temperature of the
compressor is not 10°C higher than the
condensing temperature and there is no other
faults, such as an excessive charge of refrigerant
and others.}
• Fault diagnosis of DC fan motor
About fan motor fault diagnosis.
When ISPM/DIP-IPM is faulty and Alarm 53 appears, the fan motor may also be damaged. To prevent ISPM/DIP-IPM
damage which may result from operation combined with a faulty fan motor, check also if the fan motor is not damaged
when ISPM/DIP-IPM is replaced.
C A U T I O N
– For the shake of safety, turn OFF the power before start working.
– Working/checking with the power ON may disturb correct diagnosis and may result in failure.
Models for ES:
DC motor(s) included in different models:
Model Pieces
RAS-(2/2.5)HVRN1(E) 1
RAS-3HVRNS 1
RAS-(4-6)HVRNS1E 1
RAS-(8/10)HRNSE 1
Fault diagnosis procedure
1 Remove fan motor connectors from the control PCB ISPM or DIP-IPM and turn the fan motor shaft by hand.
Normal: Fan motor shaft turns smoothly.
Faulty: No continuous rotary torque movement felt when turning the motor by hand. This occurs because the internal magnet
of the fan motor breaks the movement when the internal electronic circuit of the fan motor has a short-circuit fault
2 Measure the fan motor resistance using a tester.
Measurement procedure:
1. Remove the fan motor connector from the control PCB, ISPM or DIP-IPM.
2. Connect the black test lead of the tester to the black wire pin of the fan motor connector
3. Connect the red test lead to the wire connector pin to be checked
Results
Normal: Observed values will be close to the normal values in the table below
Faulty: Observed values will be deviated from the normal values in the table below.
Generally an open-circuit fault shows ∞, and a short-circuit fault shows several Ω-kΩ.)
Internal electronic circuit fault of the fan motor including short-circuit and breakage can be checked
8 Troubleshooting
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SMGB0060 rev. 1- 12/2010
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